The Ugly Truth About Epoxy? [Archive]

Gringo

11-11-2007, 05:07 PM

I've just finished reading Appendix C, "Superior Adhesives For the Millennium", from Larry Pardey's excellent book, "Details of Classic Boat Construction: The Hull", 2nd Edition. Mr. Pardey is refreshingly blunt and doesn't mince words in his warning about epoxy as a good-for-what-ails-you kind of marine adhesive.

For those of you who've not had a chance to read Appendix C, here's a three-point summary: 1) epoxy is not a viable adhesive in a marine environment and delaminations are becoming commonplace on boats; 2) epoxy fabricators and suppliers, while not committing outright fraud, have encouraged duplicity among boatbuilders through tall claims in advertising; 3) resorcinol glues are without sin, provided you can live with a dark glue line.

As I prepare to build my glued lapstrake Newfoundland Trap Skiff (the loveliest little boat on this planet. Visit Walter Simmons' Duck Trap site and see if you don't agree: http://www.duck-trap.com/2002nts.html), I suddenly find myself feeling rather verklempt. Sure, everybody agrees epoxy is messy, expensive and, if not properly handled, unhealthy. But, until reading Appendix C, I'd never had reason to doubt the omnipotence of this God of All Glues.

Does epoxy as a marine adhesive really merit Pardey's dismal opinion of it? Or can we categorize Appendix C as merely some well-intentioned hubris from an arch-traditionalist yachtsman sceptical of any nautical practice less than a century old?

Would love to get some opinions on this before I go out and buy two thousand dollars' worth of epoxy resin, hardener, plastic gloves, paper cups, solvent, towels, respirator and coveralls.

Many Thanks.

Steve Grube

Bob Cleek

11-11-2007, 05:26 PM

Like many, I thought epoxy was the greatest thing since sliced bread, but now I'd say Pardey is absolutely right. No question about it. That said, there are lots of good uses for epoxy... but remember that "epoxy" is a generic term and not a specific term for all "epoxy adhesives," or "epoxy fillers" or "epoxy sealers." As an adhesive, epoxy has many limitations in the marine environment. It is great for gluing together drawers as opposed to cutting dovetails, for example. As a general purpose construction adhesive, for lamination or gluing up spars, for example, it is wildly dependent upon the care taken in its use. Most importantly, a thick mix, as would be used for a lot of structural gluing, will not soak into the wood very well. This means you have a really strong bonding agent that is only holding on to a very, very, thin section of the wood surface. The epoxy will hold forever, but the millimicron thick layer of wood it is attached to will pull away from the rest rather easily. Moisture will certainly make the wood, though not the epoxy, weaker, hastening the process. The solution, of course, is to use a proper epoxy penetrating sealer on the pieces to be joined before gluing with a COMPATIBLE epoxy adhesive. In that fashion, the adhesive is stuck to a much thicker (you hope!) section of epoxy saturated wood.

For gluing softer wood especially, urea formaldehyde glues (Resorcinol) are better options and they are waterproof. These are less forgiving and demand better joints and greater clamping pressures, but are much more dependable. There are also such products on the market now that are gap filling. (Aerodux)

Like Pardey, who has probably seen many more, I've seen several professionally built boats now with epoxy laminated keels and stems which have delaminated terribly. No one seems to know why. Some layers may be holding great, while others fall apart. A keel I know of held together wonderfully during a few years of construction, but turned up badly delaminated when the boat was first hauled a few weeks after launch to swap props. I once epoxied a 2" square by 6" long block of wood to a similar piece to act as a support for a cockpit locker restraining spring (to hold it up when raised). A couple of months later, I found it simply hanging down from the spring it was attached to, having completely lost its bond. I have no idea why. I epoxied it back in place and it seems to be holding. This application was of little consequence, but I wouldn't want the same thing happening to my keel, stem, sternpost or frames...

Ian McColgin

11-11-2007, 05:29 PM

Nothing I've epoxied has failed, but the oldest item still in use is only 35 years old.

Epoxy cannot be used wrongly or ignorantly. Every problem I've seen with epoxy is the result of improper or inappropriate application. For example, John Gardner warned back in the early '70's against attempting to bond 2x2's in an ashcroft patter with epoxy as the swelling and shrinking would create interesting stress failures. All too many folk have mixed poorly, overclamped, starved joints, and anything else they could think of to make the join fail.

Epoxy is marvelously forgiving, as are screws. Just as it's inexpedient to use drywall screws to hold 3/4" planks on the frames, so also it's silly to think that you can epoxy the engin mounts to the stringers or to set lexan in a porthole with epoxy.

The Pardy's are right that epoxy does not meet USCG "waterproof" standard. That standard involves boiling the joint because the testers don't want to wait years to see a failure. Epoxy is vulnerable to heat. If you don't boil your boat, it'll be fine.

My name is Ian and I'm not a recovering epoxyholic.

Jay Greer

11-11-2007, 06:28 PM

While I have seen a lot of epoxy joints delaminate over the years, I still use it for jobs that I consider to be safe and within its holding parameters. One place I avoid its use is for gluing deck and hull plugs!
Over and over I have seen it fail so often when used for this and many other purposes that I have become weary of making comment when the discussion of its use arises. Some one always claims to be the exception to the compounded evidence concerning its questionable longevity. I did use it for gluing up the spliced mast for "Bright Star" last summer as the entire mast had been glued with it at one time. I used like glue for like glue in this case. I will comment that both the mizzen and main masts had also delaminated and required splining as well as screws to hold them together. Knowing that I will build new masts for the boat before the old ones fail again, I took the easy way out doing the repair work and used epoxy.
Jay

JimD

11-11-2007, 06:42 PM

For gluing softer wood especially, urea formaldehyde glues (Resorcinol) are better options and they are waterproof. .

Sure about that? I think resourcinol is a phenol formaldehyde, not urea formaldehyde.

Frank Wentzel

11-11-2007, 06:55 PM

The Gougeon brother's Adagio, built in 1969, is still racing. There were no fasteners used in the construction of her hull. Used properly, within its limits, epoxy will give anything else a run for your money. Of course, if 38 years and still racing is not considered adequate testing, I guess I will have to concede the point.

Although it may be considered blasphemy to suggest this, maybe Larry Pardy does not know how to properly use epoxy. I'm sure Jan and Mead would be willing to give him a few pointers.

/// Frank ///

Todd Bradshaw

11-11-2007, 07:41 PM

Agreed. Perhaps the title "Classic Boat Construction" might be a tip-off as trying to mix epoxy into traditional construction methods must be done very carefully. The epoxy building techniques that seem to produce wooden boats that last tend to be quite different from many classic construction methods. Also keep in mind that a relatively small percentage of the people sticking boats together with epoxy resin really have a great handle on what they're doing or the fine points of using it. You can make a really crappy boat using epoxy and it will probably float and last for a while, but a well made one that's going to last many years takes more knowledge and skill.

Bob Smalser

11-11-2007, 08:00 PM

First, you're not listening to the author, you're listening to someone quote the author, perhaps even out of context. I suspect this more refers to the larger yards building large, glued-spruce yachts in production runs than one-off canoe and small boat builders.

Second, questioning an experienced craftsman's ability to mix something as simple as 1:1 or 4:1 is absurd.

Third, my observations of those who've had failures with glue and wood is that they get the wood part wrong, not the glue part. That includes me. If you want to question something, question how someone otherwise experienced but with glue failures is reading the moisture content in his wood as part of his glue decision. Epoxy demands dry wood. Here's a comment similar but in reverse:

...if you can mix epoxy, you can mix resorcinol. Their cost is similar, so I don't know what you're so afraid of. All you need for success are a few more clamps and an old heat blanket from Good Will.

Resorcinol glues significantly wetter wood than epoxy does, and to a proven, below-waterline standard. No lick on epoxy, but in boatbuilding, that's priceless.

Cuyahoga Chuck

11-11-2007, 08:19 PM

Ya' mean I've been risking death all these years? The epoxy scarf that goes all the way around the middle of my kayak is going to pull apart and leave me hanging on to an over sized wooden ice cream cone? And the the four half sheets of plywood I scarfed together for my pirogue might have given up when I was out in Lake Superior? The spirits of Gitchee-Goomie must have been with me that day! Then there's "Rubber Ducky", the pram in my avatar. The only metal in the whole thing is in the rudder hardware. What will I do without "Rubber Ducky"?
Am I just an epoxy fool in a Glue and Screw world?
The Dutchman was right. "Old too soon and schmart too late."
Gotta' head down a to Tru-Value and buy some screwdrivers.

Tom Lathrop

11-11-2007, 09:04 PM

Different builders have different gurus. If yours is Pardey you will accept his word as gospel. In areas where he is knowledgeable, he may be the expert. On epoxy, it is clear to me that he is ignorant. Most likely he has never used epoxy on the kind of boat construction and in the tasks for which it is intended. If he makes claims, as it was stated that he did in his book, it is an indication of ignorance.

Ignorance is not so much a problem since it can be cured by education. Refusal to become educated is another issue and may be terminal. I build houses, furniture, boats and other projects with wood and use just about all kinds of glues, adhesives and sealants. Epoxy is one of the best and most forgiving. None are perfect in all cases and Pardey's Resorcinol would be completely useless in the boat I am building now although it was the first choice in the aircraft propeller I built for a friend's experimental plane earlier this year.

Titebond aliphatic is one I use a lot although I am cautioned by Bob Smalser's testing of compatibility in repairs that he made.

Recurring diatribes against epoxy says a lot more about the authors of same than it does about glue. Use of proper tools, materials and building methods are needed in every kind of project. If any are used outside their proper fields, it is the fault of the user and not the specifics.

Jay Greer

11-12-2007, 12:24 AM

CK 17

11-12-2007, 12:27 AM

Well, judging from the title, epoxy didn't stand a chance. I've built 6 boats with the stuff. Í have had some hard wood bonding problems. However, while the 3 strip built kayaks, 2 sail boats I've built were not exactly works of art, they are still together.

I swear by the stuff. Use it safely. Follow the best practices in the gougeon bros. book and you'll be ok

RodB

11-12-2007, 12:27 AM

Just a few thoughts randomly stated...

First, some of the previous comments are made by some of the most experienced forumites around, and its hard to disagree with much of what has been said.

Wow, interesting comments. I have the book in question and read said appendix...and at first was quite disgruntled as all my perceptions about epoxy were put to some level of doubt. I immediately began a quest to get more information as to the real world evidence relating to catastrophic failure in boatbuilding using epoxy. I talked to the designer of my boat, Tracy Obrien, for starters, who has built over 60 boats using epoxy in his lifetime till now and most are still around and are doing just fine. Additionally, I asked Tracy, hypothetically speaking, if he was going to invest $300,000 dollars in a sailboat, what would it be his choice of materials and building methods...his reply, "top notch wood materials....and cold molded with epoxy".

I spent some time talking to the Gougeon Brother's technical dept and reading available literature from them... (especially articles on longevity and failures) (I know, biased big time, right?) and just about any designer/builder I knew of that designed and built boats with modern epoxy composite building methodologies... (Ruel Parker, Mark Smaalders, Paul Gartsides etc). The Gougeon Brothers have some great essays on failures long term, but most failures that I read about related to the woods used, not the epoxy.

I posted threads on this forum on building boats for hot climate/tropical climate longevity...and got some great responses from folks in such environments with specific anecdotal details on the failures they had seen and what type of construction they recommended (encapsulated epoxy composite construction).

I found some folks had little faith in epoxy no matter what happens in the real world. Many folks are persuaded by direct observations at some points in their career, and will never change their position no matter what...that is not to say there are plenty of failures with said materials...its just important to be able to objectively examine the problem to determine exactly how it was built and why the failure.

I remember Tom MacNaughton had some comments pertaining to this in his diatribe supporting strip-planking in the debate with Paul Gartsides a few years ago...again, proper building techniques was stated to be vital in such an endeavor.

Additionally, those who live and breath in the epoxy world cannot understand how those on the other side of this issue will not take advantage of modern technological advances.

There are more differing opinions on this subject than differing doctors or mechanics agreeing on a diagnosis for a patient or an auto respectively.

I also have spent alot of time helping with and documenting the building of Peterson's "Susan" by a local professional builder/engineer who is extremely knowledgable in the concepts of composites both in the marine and the aerospace industries. This particular builder has built several classic designs using modern strip/cold molded techniques...with design modifications to match the modern materials.

For me, it really comes down to what some of the others have said here... using epoxy with the right materials, the right techniques, and the right type of design is what it is all about.

Is it so simple that one joint stands up perfectly over the years and another joint just inches away fails simply due to moisture content at the time of bonding...or differential ingress of moisture over time? What about possible contamination of he surface to be laminated? Would that be one of the most common reasons for failure? Wouldn't it be a very interesting survey to ascertain how many professionally built cold molded or strip/cold molded boats that were built in the last 10 years will have a serious failure in the next 20 years?

I will say that reading Pardey's appendix did persuade me that if building a mast for a sailboat, thickened resourcinol would be a better choice than epoxy... especially in a situation where extreme conditions exist (lots of stress plus heat, cold, and moisture cycling) IMHO...

RodB

George Roberts

11-12-2007, 12:38 AM

Proper engineering leads to proper use of materials.

Epoxy and resourcinol when properly used have long lives. When improperly used have shorter lives.

Jay Greer

11-12-2007, 01:26 AM

A very famous yacht which is some 110' LOA was built on the East coast by a reputable builder who used cold molded epoxy saturation construction. The area that would be considered the garboard never set up properly for some unknown reason. It created such problems that the owner finally sold the boat just to be rid of the difficulties involving repair.
I am one who advocates cold mold construction and consider it to be an excellent means of hull building due to the saturation of the plys. However, as mentioned above, some times something goes wrong causing disasterous results. I would never consider using it for laminating keel timbers or frames. Again I admit doing a mast repair on my own boat using epoxy. I do not expect it to last! New masts are in the works so it does not matter.
Jay

RodB

11-12-2007, 01:40 AM

Jay,

The builder of Peterson's "Susan" laminated the backbone and keelson using epoxy but placed several countersunk/buried galvanized 1/2" bolts with washers throughout the length of the hull bottom for insurance... With all the stresses imposed by the 4000# + keel that will bolt up through the bottom structure, I am sure the bolts were a good idea.

http://pic15.picturetrail.com:80/VOL595/4284825/9384890/134875442.jpg

http://i100.photobucket.com/albums/m13/RodBrink/Bobdrillingfloorsforboltstodeadwood.jpg

http://i100.photobucket.com/albums/m13/RodBrink/Floordrilledforbolts-72-1.jpg

Note filled countersink holes where 1/2" galvanized bolts were installed...
http://i100.photobucket.com/albums/m13/RodBrink/closeupballastkeelcradleglueup-72.jpg

Gringo,
Checked out the design you are building and thought the following thread would give you lots of peace of mind in building with epoxy...

Canoe yawl build his "Wenda" with Sapele 1/2" marine ply and although built glued ply lap, the interior of the boat was finished out with traditional construction. You can contact him for more details on his hull's construction.

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=2249&highlight=Wenda

http://www.canoeyawl.com/building-sally.htm

http://www.canoeyawl.com/

RB

mike hanyi

11-12-2007, 01:58 AM

Oh you really found the most knowledgeable person to quote on epoxy....I do remember some book of theirs claiming harnesses were no good as it gives false security of being safe.
And heavy stout boats are the best for off shore, Boy I was much happier outrunning the gale in the 60ft Swan 10 years ago on our way to bermuda.
just because it is published does not mean it is true!

Larry Pardey - slightly full of sh-t!
old farts that happen to sail around the world a few times and wrote a book to support them.

I agree that most people are zombied into the belief that you MUST use epoxy in a boat, I get tired of people asking me if Riviera is epoxied over, Epoxy in the correct hands can yeild great workmanship,
We just finished fairing the hull of a cutts and case method 32ft motorboat, no real fastners-just epoxy- weight of hull 585 kilos with required reinforcement.-try that with traditional build
Baltic yachts- 100% epoxy and cloth
round the world racers- epoxy and carbon

Im about to laminate the frames which will be the molds of my next boat, I have no fear thay will last as the owner knows he must keep the finish of the boat for it to last.

sorry larry- your preaching is incorrect

P.L.Lenihan

11-12-2007, 03:13 AM

Let's see, a fellow once built,using an age old building method, a 22 footer,based on a hundred year old British workboat and proceeded to sail her around the world over several years.During this engineless cruise,"they" write several books about their adventures and acquire a nice fan based following of folks with wanderlust. After some time,this same fellow, proceeds to build the same boat all over again, only this time she is a bit bigger,a bit more refined and the budget is a bit looser.This means he can now build/do fancy expensive things like bronze floors,top shelf lumber etc. His 2 boats are little more then basic text book examples of traditional boat building except for the yachty touches which help distinguish them from their work boat heritage. I fail to see how building two traditional boats makes him or anyone else an expert when there are many professional builders who routinely produce boats, using the very same methods,over and over again without all the published acclaim. For that matter, there are hundreds of dedicated amateurs (many on this very forum)who have produced more boats individually then he has in his life time,yet their voices go unheard.
Just to be clear, Pardey knows how to build a boat using an age old,time proven method.All this means is that he was a good student and learnt well how to copy and repeat the lessons of past generations of traditional boat builders.There was no innovation,invention or creative genius involved with his two boats. Anyone wishing to build a boat using strictly tradional methods will not go wrong in following his presentation.

However, boatbuilding with epoxy involves a very different approach in methodologies and techniques. It is not an insignificant waste of time to study best methods and techniques offered in,amongst others, The Gougeon Brothers text on the W.E.S.T system. There too is a serious reason it is refered to as a Saturation technique. The wood must be protected as much as possible against moisture,be it entering the wood or leaving it. Similarly, joints and laminates benefit greatly from pre-wetting, as this key step helps in the fight against glue starved joints, as will adding a slight hollowing or dishing out of the faying surface.Freshly sanded or roughed up surfaces will hold and take up epoxy better then freshly planed surfaces.Correct temperatures and thorough mixing of epoxy also goes a long long way toward success.
Epoxy boatbuilding is a relatively new approach to boat building(compared to eons old traditional boatbuilding) and has so far proven itself capable of standing up to the rigors of boat use, if done right.

Thus, I would be inclined to suggest that the real " ugly truth about epoxy" is simply this; many who use it, have not taken the time to fully understand it, do not always use it correctly and have not learnt how to use appropriate techniques when assembling a boat with this product.
Mind you, alot of the advertising hype surrounding epoxy did not really help the amateur as it lead one to believe that epoxy was the next best thing to sliced bread.Gap filling it may be, but it will not correct sloppy building habits or practices. :)

Peter

Don Z.

11-12-2007, 05:25 AM

Seventeen posts in less than twelve hours. Clearly there are some strong feelings on this subject.

I'm not an expert on this subject. The subjects on which I would classify myself as an expert are best not spoken of in this forum.

That understood... all that I know is what I've experienced... the second O in "OODA". Thus, all I know on this particular subject is that I own a boat cold molded in 1983, this boat has been raced heavily, and while like any twenty five year old boat that's been raced heavily, it requires some maintenance... I have not seen delamination anywhere.

This experience would judge Mr. Pardey's thesis as "Not Proven".

werner

11-12-2007, 05:49 AM

link to the text so at least some comments to it will stick
http://www.cpadhesives.com/media/ClassicBoatAppendix.pdf

Jay Greer

11-12-2007, 08:51 AM

I do know for a fact that Larry Pardey did extensive scientific research into the properties of various adhesives. In some cases was in close contact with various manufactures before publishing his opinions on the positive and negitive characteristics of various glues.
Jay

willmarsh3

11-12-2007, 09:26 AM

I have built two boats using West epoxy. I've used it on a third. I have not had any problems what so ever. But I have followed all the proper application techniques mentioned in this thread. It is an essential part of Sam Devlin's designs.

Jay Greer

11-12-2007, 09:53 AM

I am of the belief that a properly designed and constructed wooden hull should last nearly one hundred years. The discussion here is based upon current results involving the use of epoxy as a major construction adhesive. And not, on longevity resulting from the extended aging of glued components glued with epoxy. While none of the modern boats have really been around long enough to show how father time treats these vessels, many older epoxy glued boats are now needing expensive repairs of glued components. "Windward Passage" is one such vessel. If a man loves his boat and can afford such repairs, the materials it is built of are of no consequence other than to be expensive.
Jay

Audasea

11-12-2007, 09:54 AM

Interesting thread. Timely too, as I started a thread on the health issues of working with epoxy. And somewhere near hear a thread on thickening agents for epoxy. Sawdust off the floor? Cement? I've lost tract of how many threads I've read about joint failures due to bad mixing techniques. How much of this is product failure and how much is operator error? It also seems to me that much of the complaint relates to failures of structural wood laminations, which comes with inherent internal stresses and movement due to shrinking and swelling. Plywood is another story.

I have an open mind on this, and I value Mr. Pardey's opinion on anything, but here is the fault. He suggests using the European product called Aerodux or Cascophen. They are not the same product:

http://www.chemical-supermarket.com/Resorcinol_Adhesives-c14.html?gclid=CLK1sb3O148CFRquQAodkidVzA

I'm guessing you go with the Aerodux.

The Pardey article says these are available in the US from Jamestown Distributors. They are not. I have the most recent catalog in front of me and they only have one Resorcinol product available, the US DAP version and it's $28 per pint. Not exactly cheap.

So assuming I want to use it (I do want samples to test it), what is a guy to do? I would think that if it's as good as they say, it would be available everywhere. Should I be starting my own boutique business selling boat glue?

BTW, what delamination problem did they have on Taleisin?

Dale Genther

11-12-2007, 10:58 AM

Audasea - I found Aerodux 500 at www.chemical-supermarket.com
$125 per two quart kit.

Bob Smalser

11-12-2007, 11:11 AM

RodB

11-12-2007, 11:17 AM

Not long after I first read Pardey's book I happened to see an advertisment for Aerodux 500 from a guy in New York who had purchased a 55 gal drum of the stuff and was trying to sell off some to recapture some of his costs from importing the product from the UK. He had quite a bit more than he needed for the project he was working on. I don't remember exactly but I think he wanted about $80 for a gallon of the stuff and he sent me a copy of the printed instructions that came with it... I kinda wanted some for testing for personal experience... BTW, the shelf life was listed as a year...and I ended up passing on the offer figuring I can always get some later, and hopefully it would be available here in the USA sooner or later???

Thanks Dale:

http://www.chemical-supermarket.com/Aerodux-500-Fast-Cure-p101.html

http://www.chemical-supermarket.com/Resorcinol-Adhesive-Chemistry-c150.html

http://i40.photobucket.com/albums/e239/Prestoboat/Aerodux-500info.jpg

RB

Don Z.

11-12-2007, 11:35 AM

Here is basic resorcinol for $115 a gallon:

http://www.cpadhesives.com/Online_Store.php?thiscat=1&=SID

The only real differences between using it and epoxy are a couple of clamps and an old heat blanket from Good Will.

I guess my question then would be...
Clearly, "stapling" a cold molded hull would not have enough clamping pressure, if I were using Resorcinol... Would vacuum bagging be enough?

Bob Cleek

11-12-2007, 11:35 AM

Lin and Larry may well have written more books than they've built boats, but the issue isn't whether they are "experts" or not. The question is whether what Larry said about epoxy is TRUE. While I don't always agree with everything any one person may say, in this instance, Pardey is right, as far as it goes. As much trouble and work as one puts into building a boat, it just doesn't make sense to take chances on materials that aren't the most certain of all.

If you must consider the source, rather than the source's facts, consider that Pardey has spent the better part of his lifetime working his way around the world REPAIRING boats for a living. (Don't think for a minute they ever got rich on their books... there just isn't enough of a market for them.) I'd actually trust his reports on what doesn't work more than his reports of what does.

It is important to recognize that Pardey was talking about epoxy ue in traditional construction. Nontraditional epoxy lamination is another animal entirely. Whether those techniques will stand the test of time remains to be seen. For my money, small boats built of saturated epoxy are simply too heavy. Big boats built of saturated epoxy are just too expensive a bet for me to take. It's none of my business, however, how somebody else wants to spend their money. And for those who are passionately attached to epoxy, consider that, unlike the Gougeons, Pardey doesn't make his living selling resorcinol glue.

willmarsh3

11-12-2007, 12:14 PM

I find this to be a really interesting thread. I have worked with West epoxy and I am happy with the results. I respect Lin and Larry Pardey. I have read several of their books. I have toured both Taliesan and Seraphym at boat shows and I see that they are really well built and cared for boats. So when they say something like this it really gets my attention.

How does this fit with my experiences building boats?

I think my answer would be this: I think that epoxy would not be the best choice for repair of traditionally constructed boats. This is because it is impossible to totally encapsulate the wood as the Gougeon brothers advocate. Also I think that traditional construction would flex differently than cold molded or S&G. Is that true?
I know that epoxy doesn't hold up well if the joint is subject to continual bending forces. Hence the need for scarfing.

Bob Smalser

11-12-2007, 12:16 PM

I guess my question then would be...
Clearly, "stapling" a cold molded hull would not have enough clamping pressure, if I were using Resorcinol... Would vacuum bagging be enough?

That's where I'd be on the phone or email to the Aerodux engineers in the UK. If their #500 resorcinol will fill a 16th-inch gap, I wouldn't think staples would be a problem. let alone vacuum bagging. Given a valid choice, I'd choose resorcinol over epoxy for anything structural.

pcford

11-12-2007, 12:43 PM

Some years ago, WB carried an article about use of epoxy in traditional construction. The point of the article, if my hazy memory serves, is that epoxy, in situations where moisture cycling occurs, is not to be trusted completing. Thus, I would certainly agree with the above opinion of Mr. Cleek. Bob Smalser's comments on the white oak/epoxy thread are not exactly on point in that instance, but in general, I concur that moisture cycling can be a problem with epoxy used in traditional construction.

JimD

11-12-2007, 01:04 PM

... For my money, small boats built of saturated epoxy are simply too heavy...

I would have thought the opposite is true. Trad carvel or lapstrake require heavier construction that more than accounts for a few pounds of epoxy.

JimD

11-12-2007, 01:09 PM

...a reputable builder [who] used cold molded epoxy saturation construction. The area that would be considered the garboard never set up properly for some unknown reason. ..Jay

Now that is interesting. How many times have builders posted to the forum saying "Help! My epoxy won't cure!"? And how many times has it ever turned out to be anything other than human error?

werner

11-12-2007, 03:26 PM

Tom Lathrop

11-12-2007, 03:29 PM

I would have thought the opposite is true. Trad carvel or lapstrake require heavier construction that more than accounts for a few pounds of epoxy.

Well, Nessmuk's Sary Gamp could not likely be built lighter using epoxy than as it was. Of course Sary Gamp was near to being a disposable boat since it was built very lightly and required great care in use. So in at least one case out of millions Mr. Cleek is probably correct. :D

paladin

11-12-2007, 04:06 PM

Well....helll.......may as well drop in mi dos centavos........
I have the very most respect for the Pardey's and their accomplishments.......and Larry has probably repaired more boats than I've been on........I may have built more boats than he...and not one (unless you count the first plywood sunfish) has been conventional construction. I started in the late 50's using plywood, rescorcinol, plastic resin glue, and fir.......last I heard he boat was still being used, and my first plywood pram dink was built that way until a couple of years ago when my brother in law so advised me that he had successfully finally dragged the bottom out of it by hauling it over gravel when going fishing.......I can't claim 50 or a hundred years...but call Jim Brown in North, Virginia and ask him how Scrimshaw is holding together. I started building her in March 1969 and to the best of my knowledge none of the joints have delaminated......I was one of the first epoxy/ply/cold moulded builders....call the Guedjons and ask them if they know a Chuck Phillips and how far back do they think I have been building this way.....long before their Adagio. The U.S. Navy developed laminated structures using epoxy long before it became common usage in yacht building. If the data that was accrued, and the information generated by McGruers in Scotland is properly followed, I think that the epoxy will last as well as any other material, and I can only go back about 50 years. There's only one place where I would be skeptical, and that is in the building of spars...but it will depend on the technology. A multihull spar is more rigid in most cases than one used on a monohull, the spar needs to flex to some degree. Most epoxies are too rigid for spar use. When Gerry Schindler formulated T-88 he did it with wood movement in mind......I immediately gave up on W.E.S.T. stuff and went to T-88. I have never had a spar failure, and I have built a few using T-88, I have laminated centerboards, keels, stems etc, but I have also avoided certain types of wood when building, except in non structural cosmetic work. The mention of additives is also a problem. When gluing you need virgin glue, paint on the first coat prior to assembly, wait until just before setup and put fresh epoxy on both surfaces then attach.....many of the techniques that are in the W.E.S.T. manuals were developed by multihull builders elsewhere in the world......the proper material needs proper attention to be properly attached........epoxy may have no place in the construction methods that Larry Pardey professes......it doesn't mean that it's a bad material. Todays buzz words in the yachtie crowd in Annapolis are titanium fittings....but do you want to go offshore, sailing around the world with titanium fittings on your boat. They may be great in some offshore hell bent for leather racing events so that someone drags you back when something breaks....but if you're the only guy there and you have to fix it, I'm gonna use bronze.....

Jay Greer

11-12-2007, 04:15 PM

[QUOTE His 2 boats are little more then basic text book examples of traditional boat building except for the yachty touches which help distinguish them from their work boat heritage. I fail to see how building two traditional boats makes him or anyone else an expert when there are many professional builders who routinely produce boats, using the very same methods,over and over again without all the published acclaim. For that matter, there are hundreds of dedicated amateurs (many on this very forum)who have produced more boats individually then he has in his life time,yet their voices go unheard.]

I know for a fact the Larry Pardey was a fully qualified professional boat builder long before he decided to build a boat for himself. It was his knowledge and fine craftsmanship that gained him the respect and assistance of Lyle Hess, the designer of both of Larry and Lynn's boats.
Jay

11-12-2007, 05:19 PM

I think I can honestly say that if I had not epoxied the inside of the hull of Redwing nearly 20 years ago, it would have been firewood last year.
I have built several stich and tape boats and have never had any problems with delamination. I have had wooden fittings break but that was not the fault of the epoxy.
Larry Pardey is in my opinion a particularly fine craftsman capable of joinery suited to the use of Resorcinol. I on the other hand am not of the cigarette paper brigade and therefore use and recommend epoxy.

Robmill0605

11-12-2007, 05:32 PM

Someone told me once:

" don't stick yer head up in the middle of a sh*t fight"

Ignoring this advice here's my .02. on epoxy.
I'm building an epoxy boat and here are the mistakes I've made in using it.
Epoxy is not a substitute for proper fasteners. so I went back and used silicon bronze screws and keel/stem bolts in my laminations.
It's taken me more work than it's been worth fooling with it.
Secondly, epoxy does not penetrate the fibers of the wood very much if the bond of the epoxy is the only thing between you and Davy Jone's Locker you are in trouble if it should delaminate.
The third mistake was using laminates that are way too thick. In cold molding the laminates have to be very thin to properly bond.
Also, if I ever cold mold again I will vacuum bag the hull.
Who knows if there is an even bond between the laminates as the fasteners only apply local clamping pressure.
While I'm not worried about it since this is a runabout and not an ocean sailer, I've learned that epoxy is not the 'miracle' in modern boat building .
Next project, I'm building the boat in the traditional manner.

.

Ken Hutchins

11-12-2007, 05:49 PM

Would love to get some opinions on this before I go out and buy two thousand dollars' worth of epoxy resin, hardener, plastic gloves, paper cups, solvent, towels, respirator and coveralls.

Many Thanks.

Steve Grube

$250 worth of resorcinol and $120 worth on 3M 5200 in TALLY HO 36' long, 16 tons. Clean up the resorcinol with the wonder solvent H2O,:) I'm still using the same 2 'disposible' brushes 1 big and 1 small.:D Clean up 5200 the mineral spirits. :)

11-12-2007, 06:24 PM

Botecote epoxy washes up in warm water.
Of course if your joinery is up to the task then use Resorcinol, I would.
I also agree with using fastenings, nothing wrong with the belt and braces approach.

John R - Kitenui

11-12-2007, 07:05 PM

one of the first failures I had with epoxy was with wood getting wet and then drying then getting wet then drying etc etc. The wood expands and contracts (swells and shrinks if you prefer ) as the moisture content varies. The epoxy does not change dimensions with moisture content of the timber therefore the wood epoxy bond fails.
If you can seal the structure so moisture does not enter the timber the bond should not fail for this reason.
Epoxy is not resistant to ultra violent radiation. This can be a common cause of failure in epoxy glued spars if the varnish is not maintained to uv protection perfection, and once the glue starts to deteriorate water penetrates and the above scenario takes over. dry ,wet,dry,wet,shrink,swell, etc.

kulas44

11-12-2007, 07:16 PM

A quote from Dave Gerr's otherwise excellent book, elements of Boat Strength, paragraph title, "Applications of Liquid Joinery". His overzealous support of epoxy lost a lot of respect from me. I like the stuff, use it everyday, and rely on it, in it's miriad forms from 1 to 1 cheap stuff for filler to 5 to 1 for structural use. I don't glue wood to wood with it, cause I like urethane, PL Premium to be exact. It's just more convenient. I thicken, thin, heat, and cool epoxy, depending on what I need. If you are expecting it to do something and then it doesn't do it, where is the fault, you or the glue ? Bolts, rivets and screws are really good backup. My epoxy doesn't fail because I won't give it the chance.

paladin

11-12-2007, 07:24 PM

I personally think that a lot of the problems with epoxy are that there's been too much hype about what it will and will not do.....from personal experience. Having used resorcinol/plastic resin/epoxies and being super cautious with all three......I "knocking on a wooden head" perhaps have been lucky. I have not made sloppy joints and then tried to use the adhesive as a filler in any manner. I was taught to make everything fit without fasteners, then put in the fasteners.

Bob Smalser

11-12-2007, 07:35 PM

interesting to know ....this article gives some (scientific) clues to why epoxy (or other glues) could fail in some cases and how glue works in the boundary wood layer
http://www.fpl.fs.fed.us/documnts/pdf2006/fpl_2006_frihart004.pdf

Actually, the paper describes the FPL's parameters for describing glue failures. Honest scientists to the core and not in the business of selling glue, they aren't shy about admitting they don't have a better handle on why glues fail than most builders do.

....Wood bonding is one of the oldest applications for adhesive assembly of products. Nevertheless, the mechanism of bond failure is not as well understood as are most other adhesive applications....

….there is limited knowledge about the chemical composition of wood bonding surfaces (7,9,10). The roughness of wood aids in bonding, but it may also promote failure by enhancing interfacial stresses. It is not known how much the fractured wall and normal surface debris serves as stress concentration sites leading to fracture initiation....

...Although a number of methods are available for evaluating the failure of wood bonds, the chemical and structural complexity of wood can make it difficult to know where and why wood bonds are failing....

All those gradients between "bulk wood" "wood and adhesive interface" and "bulk adhesive" (the glueline) describe is that this...

http://pic20.picturetrail.com/VOL12/1104763/7738131/103956073.jpg

...is a stronger glue bond than this....

http://pic20.picturetrail.com/VOL12/1104763/7738131/102357761.jpg

...because it broke wood instead of just glue. They don't explain why, they just invite further research.

P.L.Lenihan

11-13-2007, 05:07 AM

[QUOTE=Jay Greer;1692483
I know for a fact the Larry Pardey was a fully qualified professional boat builder long before he decided to build a boat for himself. It was his knowledge and fine craftsmanship that gained him the respect and assistance of Lyle Hess, the designer of both of Larry and Lynn's boats.
Jay[/QUOTE]

Thank you for some background information Mr.Greer. I did not know this of Mr Pardey. While I was writing my first post, I sensed that I was perhaps over-stepping things a bit and hoped not to completely disregard Mr.Pardeys abilities as such.Thus I included this part later in the post:

"Just to be clear, Pardey knows how to build a boat using an age old,time proven method.All this means is that he was a good student and learnt well how to copy and repeat the lessons of past generations of traditional boat builders.There was no innovation,invention or creative genius involved with his two boats. Anyone wishing to build a boat using strictly tradional methods will not go wrong in following his presentation."

I do now see that my stating he "only built 2 boats" can be somewhat insulting and suggestive of a limit or the extent of someones knowledge.I stand corrected and apologize for giving this impression in light of the background information you just provided on Mr.Pardey.

Upon reading the text in question,kindly provided by a link from WERNER, a number of thoughts did occur to me regarding the epoxy failures and Mr.Pardeys real world observations.

To begin, there is a suggestion made in the appendix that 5 years seems to be an expected life span for epoxy in structural joints. I am confused that there have not been more reports of failures.

Some of the examples, like the anchor windless base on page 1 show so little epoxy remaining(1/32") that it can hardly be surprising that the darned thing flew right off. Not sure if this failure is because epoxy is not up to the job or that not enough epoxy was in the seam to begin with,thus the failure. Similarly with the de-laminated tillers and boom gallows illustrated.

As all of his observations regarding epoxy failures stem from repair work, I would be interested in knowing whether or not he was privy to the construction when new. That is, can he accurately determine that it was the epoxy that failed despite best practices or was the failure due to poor practices?
I think it important to make this distinction, especially as his observations would lead one to perhaps conclude that epoxy is not really suitable for the myriad of uses presently employed in modern boat building.

Mr.Smalser is point on regarding moisture levels in wood to be laminated or glued with epoxy. If one is not rigorus in this regard, then the internal stress of the wood may well overcome an epoxy bond.

To prevent glue starved joints, it is primordial to ensure there is enough product remaining in the joint after assembly.Pre-wetting of faying surfaces is critical to ensure the fresh wood does not leach the epoxy out of the seam,but more importantly a hollowing out or dishing of the faying surfaces is more important as the pressures of the final assembly are brought to bear.Squeeze out is alright and expected,in order to guage that there is indeed enough product in the actual seam, however without a "hollowing", one has no way of knowing what is left in the seam. On structural members and large laminates like stems,keels,stern posts etc....A 1/16" hollowing or dishing of both faying surfaces will ensure that even under the greatest clamping/bolting pressures, one is left aproximately 1/8" of internal glue line in the seam. Laminates showing less then 1/16"glue line in cross section,like the 1/32" on the windless base, can and will fail as there simply is not enough product left in the seam.

Failures I have encounter on other peoples boats seeking repairs have all too often been the result of the following:

!) improper building practices,ie; no hollowing,no pre-wetting,damp wood,too cold temperatures, wrong calibrations of metering pumps and insufficient mixing of resin and hardner.

2) unwillingness of owner/builder to"glue that sucker down",but rather just a stingy application of epoxy, "just in case" it has to be removed later for repairs.I've seen this approach on everything from rub-rails,toe-rails,sheer clamps, chine logs etc.....I kid you not!

3) a laissez-faire,slack assed attitude toward a disciplined maintenance schedule which finds protective coatings worn right off the wood,be they varnish,paint or epoxy.This of course leads to the dreaded moisture cycling and failure down the road.

and finally,

4) an incomplete understanding of what epoxy is. I have seen so many folks use the stuff like it was a varnish and proceed to top coat all their precious woods only to come home crying a year later that the darned stuff ain't no good fer nothin'. Epoxy HAS to be protected from the sun as much as possible.

Many of Mr.Pardeys repairs appear to have been done on boats living in the tropics.The combination of hot sun and salt water make it all the more important to protect and maintain all exposed surfaces. Not doing so......well you know......failure yet again :-(

I think it is a fine thing that Mr.Pardey has done with his appendix C but considering his reputation, I would have liked to see a more thorough understanding of the "failures" before permitting any conclusions, implied or otherwise.

I need to go for a beer now, my fingers are thirsty :-)

Peter

Audasea

11-13-2007, 10:01 AM

Directly above me, Peter offers a pretty good summary of what I've concluded from this thread. I'll throw in a couple more thoughts.

Backing off from what you may or may not think of Larry Pardey's conclusions, lets look at the facts (got that word from Jay :) ). THE product recommended in that article (the European made Resorcinol) is available from only one supplier in the US and it costs $125 for two quarts. That is $250 per gallon. No doubt worth it for some uses. I intend to get some.

By comparison, epoxy resins are widely available everywhere. The same Jamestown Distributors catalog that only has the US DAP resorcinol has 4 or 5 pages of epoxy resins. Advertising and marketing only works to a point. Right eventually wins out. It seems the market has spoken.

And as for the points mentioned, I think back to my first efforts working with epoxy and can recall instances where my "failures" were exactly as the Pardey article described. Those (like my failed gunwhale lamination) were my fault. I was learning. I used an overthickened mix with microfibers and clamped the snocker out of it, leaving a dry, starved joint. There was a tight bend in the lamination and it blew apart within days of me removing the clamps. From that I learned how to do it right and have had no further failures. Since then, I've made a lot of test wood joints and now the wood always fails first. Mr. Smalser's point about using "dry" wood is well taken. I'm filing that one away for future use.

One key point I think is a valid concern and that is the effect of heat. I hadn't considered "heat creep". I know System 3 recommends not painting anything with dark colors for that reason. Varnished wood in the tropics might qualify. Knowing you can pull a fastening or blow a joint apart by heating it is both a relief and a bit disconcerting. Same with UV degradation. So if you want it to hold together, you take steps to avoid both. If in doubt, paint it white!!!

As for longevity.....more anecdotal evidence:

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=71208

Read the last line of Post #28.

P.L.Lenihan

11-15-2007, 02:44 PM

To begin, there is a suggestion made in the appendix that 5 years seems to be an expected life span for epoxy in structural joints. I am confused that there have not been more reports of failures.
Peter

I've just re-read the cited article (appendix C) and note that it is 5 WEEKS and not 5 YEARS that the Gougeon Brothers Inc. suggest(page 489) that an epoxy bond will lose 40% of its strength due to 24hour/day cyclic loading. Furthermore, Mr.Pardey suggests,in brackets, that the epoxy bond will continue losing more strength due to fatigue.

Am I right to conclude that given another 5 weeks of 24 hour per day cycling, my boat will have a mere 20% strength left in the epoxy bonds, and that from there on it is a matter of shorts weeks before the bonds experience 100% failure?

The lack of reports of boats falling all apart leaves me wondering. As does the notion that a piece of wood,say a toe rail, continues to be under stress once installed, as stated in the caption of photo 4,page 489. It has always been my understanding and experience that a piece of wood bent into a curve will at first require pressure and cause stress to the piece in question but will, in several days time, have stretched and relaxed its fibers enough to no longer require pressure to assume its new bend. Perhaps Mr.Smalser could confirm or refute this notion of mine?

This topic holds great interest for me, not to discover what glues have historically worked(resorcinols etc) but rather why does epoxy appear to allegedly not stand up to the job it is advertised for. Considering the vast number of amateurs right here toilling away on their dream boats and using epoxies advertised in our hosts' magazine, it would seem to be vitally important to further discuss this topic.......no?

Peter

erster

11-15-2007, 03:03 PM

Paul G.

11-15-2007, 04:06 PM

I have never heard of a boat sinking because epoxy failed. Larry has a theory, an idea, a concept, but reality and experience does not support his claims.

Epoxy is an excellent adhesive, perhaps the issue is mixing new and old methods without understanding either.

paladin

11-15-2007, 04:08 PM

Without going into personal details......in the late 60's one of the owners of System Three (before it existed) was building a 31 foot Searunner Tri.....his wife was ill and it was mentioned to me that he was trying to got the boat in the water to take her sailing. I had a half built 31 at the time so I shipped the parts to Calif. with instructions to deliver to said person.........I have forgotten to ask if his nearly 40 year old boat has fallen apart yet.........
I would hazard a (potentially unpopular guess) that 99% of the epoxy problems are due to pilot error......
and a note.....none of my boats were painted with anything other than white or near white paint, nor were any areas of heavy timber assemble with solid wood, it was always laminated and NO dark, natural wood was used as caprails over a joint.......

werner

11-15-2007, 04:12 PM

this is imo a useful discussion,
met a lot of people working on boats thinking that ,what was previously bolted ,screwed,nailed or riveted together will now hold with epoxy.Perhaps they are right... ever worked on a traditional boat "restored "with epoxy?
think this paper is reason enough for a reasonable use and doubts of especially epoxy glue

http://www.fpl.fs.fed.us/documnts/pdf2003/friha03b.pdf

Paul G.

11-15-2007, 04:48 PM

I get the feeling that traditional workmen as opposed to woodenboat magazine buyers wouldn't labour over the issue. Why would anyone glue any joint that is going to have repeated wet/dry cycling without carefully considering the design and using mechanical fasteners if required. Building a solid wooden ship is like building a house, practicality being the formost issue. Weekend warriors building a boat with trad styling cues bickering over which glues to use, I can hear those old guys having a good laugh.

There are heaps of ply and epoxy boats going strong 30 plus years on, and for the most part the builders probably think a 20 year life as perfectly acceptable.

P.L.Lenihan

11-16-2007, 06:03 AM

Yep the rumor is true that a boat will fall apart. Be carefull out there using epoxy on wood and leaving the dock, much less even leaving a boat built with epoxy in water over about six feet if you plan on sleeping on it at night. Make sure you sleep with your hand off the edge of the bunk too.

It sure would be nice to hear your considered thoughts on this Mike or Erster. You're down in warmer, all year round boating country with some salt water exposure,no? What have your real world observations been with your own boats and have you done many repairs on epoxy assembled boats?

"A wife requires simular maintainance as a wooden hull does and will last you a very long time if you handle them with care. Show them constant attention especially when they squeak or show a frown on the working parts. They will return you many days and years of enjoyment if you work on even the smallest detail each day. If not you will find out along the way at a moments notice, especially in the worse times, there will be a serious failure from the neglect."

Knock out all the references to "a wife" and just tell it as it is; a wooden boat,in particular a pleasure yacht, to truly last forever, needs to be kept up with meticulous attention to detail. It all has to do with pride in ownership and a passion for the sport. Anything less is just pure romantic foolishness borne of lazy minds,half dead souls and deep wallets.

Nice to see you back Erster :)

Peter

erster

11-16-2007, 07:29 AM

Back? Nope, but this thread is suspect and smells to high heavens. :eek: I do not believe that this is a legitimate inquiry and a sincere thread given the history of the forum and numerous others around here.;) I will let many others speak for the issue of heat in warmer climates. Where there are some issues of webbing in glass work in some applications, mega yachts are being built and sold to numerous millionaires including J. P. Morgan, Curtis Strange, and many successfull clients such as Anheiser Bush owners all built out of epoxy and plywoods. This has been going on for several decades. Let me list several of the high profile south Florida builders. Feel free to scan their websites and contact them for some real life reports of what truely takes place in the world of epoxy subjected to the worlds biggest washing machines with peoples' lives at stake each day and for many years.
These are south Florida builders with decades of builds depending on epoxy to last and not fatigue over the course of fity years in some cases. There are others too. Just google builders in Florida for further evidence, too.
http://www.merrittboat.com/

http://www.rybovich.com/Default.aspx?p=DynamicModule&pageid=228083&ssid=77387&vnf=1

Please scan this site as it actually shows boats and the building method thats being used everyday depending on epoxy to keep lives from Davey Jones locker.
http://www.jimsmithboats.net/home.html

Take a look across the front of these cabins which are an extention of the tinted windows along the sides. In the business of maintainance this is known to us as a black solar panel in multi-million dollar boats. These boats spend a lot of time underway fishing along the equator of the world.
http://www.jimsmithboats.net/images/a.jpg

I personally own and have owned numerous dark hulls and have risk life and limb in epoxy and yes junk plywoods such as Luan:eek:. eight dollar stuff encapsulated with fiberglass and epoxy. My recent experiment consists of a Aristo-Blue hull, faired with MIRCROLIGHT, a west system product which is forbidden to be used under dark paints by the manufacturer themselves. I personally built this hull for an experiement in 1993 as a fishing hull for my ownself to test the limits of some suspect items combining them with all the wrong stuff on purpose. I cannot tell you how many hours this hull has spent in tropical waters and climates such as Key West for two years being stored on concrete and asphalt surfaces in the middle of July. I would hate to know now that after almost fifty years of boat work for some boat builders still in the business using all forms of the goop, that now we read that epoxy is crap. While epoxy builds and the use of epoxy come with building methods appropiate to the use of epoxy, this is no difference than telling many of the purists that using cotton is crap to its appropiate use after many years of evidence tells us a different story. The use of cotton would never be used in laminating thin veneers no more than the use of epoxy should be used in the glue up of 1 inch solid wood planking and expect the same results either. Sometimes you can get away with it and is done regually in strip planking now with numerous successfull builds.

There can be catastropic failures from the use of epoxy in carvel planked hulls no difference than the improper use of cotton where it should not be used either.

For some reason I can no longer link any photos from my stored album or I would show you the evidence. Someone stated that there is lack of magazine articles also addressing epoxy boats failing, and the magic mix being used in the construction of some very expensive hulls, many painted black, the lightbulb of confusion for me is in the article mentioned in the original post is filled with some misinformation at the highest level, using a very high profile person to do so.

Again I do not believe that this thread serves any good for the notion for either side and either person and held in the catagory from here as misinformation and you do not need me to point it out. We all know that I do not fit the mould of normality[is that a word?].:p

There is no real magic bullet for a boat, some just shoot further allowing you to spend more time on the water if you know how to operate the high powered gun. Cotton, oakum, tar and red lead is in the same catagory as epoxy too, requiring you to know how and where to use them and to use them properly, and do work to keep a boat afloat when you see an issue or problem. Without that the 100 year old boat will also fail to keep you out of Davey Jones locker too.

paladin

11-16-2007, 09:35 AM

well said, Mike....

CliffR

11-16-2007, 09:35 AM

I have been playing with Resorcinol (DAP Marine Weldwood product) outside the specification parameters.

I have been trying to wrap my head around resorcinol use in situations where the appropriate temperatures and clamping pressures can not be achieved.

I have an oak project coming up that I had planned on using Resourcinol as the glue but I am rethinking that choice of glue. There will be M&T joints - lots of them - and they will all be critical structural joints. I am learning that resourcinol requires clamping pressures that an M&T simply won't allow because of the physics of the joint.

And I want repairability because the final product will live out of doors all year in the Northeast. Yah, I read Bob Smallser's post on Repairability.

Everyone knows: The resourcinol tech sheet says you need minim of 70-Feg-F. The tech help line guy (not a Chemical-Engineer) answered my e-mail about assembling below 70 and then curing at or above 70 by saying:

“The air temperature and materials must be at 70 degrees Fahrenheit in order for the product to activate and be of any use. The adhesive will not activate at any lower temperature nor will it form a bond if the temperature later comes above 70 degrees. Thank you again for contacting us.
Sincerely,
[name omitted]
Product Information Specialist”

OUCH~!! "be of any use" ~ ~ ~ "will not activate [...] nor form a bond if temperature later comes to 70 degrees" Those were some stern words~!!

Yet, I read often enough in forums like this about people assembling at temperatures below 70 and then applying a thermal blanket or removing the work to a heated area. Clearly, there are anecdotal experiences that seem to contradict the information I got from the DAP “Public Information Specialist.”

So:

I made a bunch of lap joints in maple using Titebond (Tit) and Resourcinol (Res). Surface area of the glue up was 1” square. I mixed and assembled and let them sit at temperatures lower than 70Def F. Average temp ranged from 56 – 67 Deg F.

Some joints were cross grain some were long grain.

The Tit group was my control group since I have a fair experience range with that glue and know what to expect of it.

A separate set of lap joints was in Res to play with the idea of Gap Filling.
The gaps were produced by cutting a saw kerf 1/8” deep and wide in an unaligned X pattern on each faces of the mating surfaces. I added some wood flour by eye to the Res glue till it was dense paste then used that paste to assemble the joint.

Clamping on all joints was nothing more than a hand spring clamp – definitely not the 200 PSI required for hardwoods and Res.

The joints were all assembled, clamped, and left to set for 20 hours (arbitrary).

After the 20 hour period The joints were examined. The Res glue squeeze out was hard but, not terribly hard. Not tacky but, a chisel sliced off a flexible peel. The Tit glue was set and hard, as it should be.

The Res glue joint sets were then placed in an area with a temperature above 70Deg-F (about 80Deg-F) and left to set for 3 hours.

After sitting at the higher temp' the Res glue squeeze out appeared harder and chiseled off with a more hard slightly brittle feel and texture.

The joints were manually stressed to breaking. The Res joints broke and the Res glue ripped off very shallow and small wood fibers from the joint faces indicating that there was almost no penetration into the fibers from the light clamp pressure. But, also indicating that the adhesion did activate and the bond did occur.

The Tit joints broke and pulled substantial splinters off the mating faces - as expected.

The force exerted to break the joints was similar enough in all of the joints that I could observe no distinction on the highly sensitive research instrument that is my arm.

The Res glue Gap Filling test joints produced some what more remarkable results.

When stressed to breakage the Res glue pulled of substantial amounts of wood. However the wood ripped from opposite faces was not torn from the gap filled area.
This led me to conclude that the paste texture of the Res glue helped prevent squeeze out and facilitated a deeper penetration of glue into the mating wood surfaces.

I think I’ll do it all over again with all the work at of above 70Def-F and this time I’ll use some hefty Forged C clamps to get clamping pressures up to spec too.

One conclusion that I am coming around to is that there may be no meaningful distinction in holding power between any of the better glues until factors other than sheer bond grip strength are introduced: such as creep, continual load, substrate expansion/contraction, and heat. Since my intended project ( of Oak) won't see much heat or immersion in water but, can't be clamped hard and won't be assembled at or above 70Deg-F, I think Epoxy is going to be the best glue choice.

Tightbond III would have been but for the repairability problems. I can always clean and reglue epoxy joints.

Tom Lathrop

11-16-2007, 09:45 AM

Ah Mike,

Well said. Watch out for "Duclin" exploding when you least expect it.:p

You could have mentioned that about 40 builders currently (and for many years) build offshore fishermen up to at least 67' for the Gulf Stream waters off Cape Hatteras in daily duty. This is in the Manteo/Wanchese area, not counting the rest of the NC coast. All of these boats are built with wood/epoxy. Some are strip but most are laminated plywood and cost $1mil to $2mil or more. Good thing they did not read advice from timber gurus.

Learn to use a material properly, no matter what it is.:)

P.L.Lenihan

11-16-2007, 03:34 PM

[QUOTE=erster;1695349]Back? Nope, but this thread is suspect and smells to high heavens. :eek: I do not believe that this is a legitimate inquiry and a sincere thread given the history of the forum and numerous others around here.;) QUOTE]

Oh,alright then Mike, in that case let me simply say that as a long time lurker and relative newbie in the posting department, I have been a long time admirer of your work and appreciate the generous spirit you have shown by sharing with this forum picture essays of your builds.Your clean and quick work is the sort of thing I aim for daily as I go about finishing up my 4th boat(a 31 foot cruiser). As to whether or not this is a legitimate inquiry or sincere thread, I hope it is and fail to see why it may be otherwise. Unfortunately, I have not got the most recent computer up-grade with that nifty scratch-n-sniff feature so haven't a clue about it smelling to the high heavens :)

I am well aware too that there are many high end commercial builders working with epoxy.Their products appear not to fail,they get rough/ tough usage on a regular basis and have been doing so for many many years.I suspect we are on the same side of this issue regarding the so called"ugly truth about epoxy".

Nevertheless, there are documents out there, as in the latest one kindly posted by WERNER from the USDA Forest Service,Forest Products Laboratory, which publish conclusions stating "Epoxies are normally durable adhesives,except in the case of wood bonding." and this "Although some adhesives give durable bonds to wood,epoxy adhesives surprisingly do not."

As a big time fan of epoxy and long time user of same, I cannot help but wonder about epoxy when confronted with these sorts of documents,including the one that started this thread off in the first place.

Mind you, I am not about to take apart my present boat just because it is built/bonded with epoxy.Even my first build is still going strong after more then 27 years. But rather, I am inclined to think that perhaps in cases where there have been reported or suspected failures,then what needs to be addressed are things like specific techniques and good,technology appropriate, building methods. Thus my interest in this thread. I cannot speak to why others participate, but I,for one, welcome and enjoy their input/discussion.

Peter

Mike Vogdes

11-16-2007, 05:00 PM

You guys sure know how to beat a dead horse.. Composite boatbuilding with epoxy is here to stay. You wanna repair your old wood hull with epoxy? Do it at your own risk.

Jay Greer

11-16-2007, 06:07 PM

erster

11-16-2007, 09:24 PM

Am I right to conclude that given another 5 weeks of 24 hour per day cycling, my boat will have a mere 20% strength left in the epoxy bonds, and that from there on it is a matter of shorts weeks before the bonds experience 100% failure?

Straight epoxy has no real strength. Epoxy is a sealer and a bonding agent. Without a filler that changes the property or a supplement like glass or glass fibers, epoxy is likened to a dummy with no brains. All bonds depends the lack of voids and on the stabilization of the components and the lack of movement which also can change in the boating enviroment with woods. This is the reason why epoxy is not recommended for bulky woods, and used mostly in thin veneered hulls, small strips of solid woods or plwood hulls. Catastropic failures in hulls built with bulky lumber is not the fault of the properties of epoxy and the lack of bonding by the epoxy. The ugly truth about epoxy when using good building practices of complete satuation is not that epoxy looses it strength as much as its components movement or in many cases the inabilty of the bulky wood to move.

I frankly do not care what Larry has to say about epoxy being crap, if the issue is only about epoxy. There is more than enough evidence at 40 plus knots in open water and builders building with epoxy that I personally know that have built with some form of it for 50 years that are still doing business with it and in the case of 27 years that disproves the idea that epoxy is crap, even in your case, Peter.;)
Check your pms.

Lets loook at what has been stated. I consider that to be a pretty broad brush no matter how you slice it. The notion that epoxy is not a viable adhesive for the marine enviroment? Yes this has been proven false by numerous years of evidence and builds. Delaminations happen in thin veneers or laminated components, not seamed construction methods. when failures happen in hulls, no matter how you slice it or dice it. I know of no classic boat builds that have many laminated hull components in them.

There are some components of thin veneers that can form some of the framing and knees, though but when done properly in complete satuation have no issues with delamination. Many keels, stem parts, and stringers in many of the larger builds incorporate lamination in lieu of natural knees and solid sawn components cut to shape.

This is what is being reported to have been written in the book.

For those of you who've not had a chance to read Appendix C, here's a three-point summary: 1) epoxy is not a viable adhesive in a marine environment and delaminations are becoming commonplace on boats; 2) epoxy fabricators and suppliers, while not committing outright fraud, have encouraged duplicity among boatbuilders through tall claims in advertising; 3) resorcinol glues are without sin, provided you can live with a dark glue line.

outaheer.;)

Boatmik

11-17-2007, 08:25 AM

I assure you that both Larry Pardy and yours truly are exteamely well versed both through practical personal experience as well as technical knowledge concerning the properties and use of most popular adhesives used in the marine industry today and in times past as well.
Jay

Pardey says one way.

The WEST people say another.

But what the WEST people said from the beginning is that you have to use the epoxy to seal all the surfaces of the timber to prevent moisture getting in and out - it is part of a "boatbuilding system".

If the moisture doesn't get in and out very quickly the moisture content stabilises and the wood doesn't move around much (or at all). If the wood doesn't move around from changing moisture then it won't overstress joints.

Traditionally built boats are completely different - they require the timber to swell to make them watertight to some extent.

Using epoxy to glue parts of a traditionally built boat makes no sense at all as the movement of the timber will break down the glued joints in very short order. And the movement of timber is what stops the boat from leaking.

So in a traditionally built boat you should restrict epoxy to drawers and things that are separate from the main structure.

The only thing that Mr Pardey did wrong was not to stipulate that he was talking about traditionally built boats.

Whether it comes from an oversight, ignorance or mischieviousness - well you have to ask Mr Pardey about that - though I have heard him talk on the subject and at the time he seemed to be ... a little biased.

But I'm biased too - you can use epoxy for boatbuilding - no worries at all, providing it is part of a consistent approach. YOu have to understand the principles.

Same too for traditional boatbuilding.

Best wishes to all!

Michael Storer

Boatmik

11-17-2007, 09:10 AM

[Nevertheless, there are documents out there, as in the latest one kindly posted by WERNER from the USDA Forest Service,Forest Products Laboratory, which publish conclusions stating "Epoxies are normally durable adhesives,except in the case of wood bonding." and this "Although some adhesives give durable bonds to wood,epoxy adhesives surprisingly do not."
Jay

Howdy Jay, Thanks for these and other comments you made.

They prompted me to look further to see if there was any new material on the subject of timber and the dreaded 'pox from the Forest Products laboratory.

My thought that Larry Pardey wrote that quite a long time ago. I remember him talking about it during a talk at ... I think it was the second Sydney Wooden Boat Festival - maybe almost 20 years ago now.

It seems that of 2006 the Forest Labs have started questioning their testing methodologies, primarily because of the conflict of two pieces of information.

That in their standard testing epoxy fails as an adhesive, yet it is used very commonly to build wooden boats of all sizes with little or no problems.

You can read about it here
http://www.fpl.fs.fed.us/documnts/pdf2006/fpl_2006_frihart003.pdf

The most interesting departure is that the standard tests are all water absorbtion tests - and epoxy boat building attempts to do its utmost to prevent exactly that.

"For epoxies the lack of bond strength occurs mostly on water exposure"

"epoxy has an inability to deal with moisture change"

but the general thrust of the above article is that if the timber is restricted from swelling - eg plywood with the two grain directions providing a stabilising influence or a coating preventing water from getting near the join then epoxy can perform very well indeed even ...

"epoxy resin – in bonding plywood specimens. The samples
were analyzed using the automated boil test for bond
durability that is now the cycle test in ASTM D 3434 (5);
this study showed the epoxy was only slightly poorer in
durability than the phenolic plywood adhesive (13). In another
study, 11 adhesives were tested using both exterior
exposure (up to 16 years) and the automated boil (up to
800 cycles) for Douglas-fir plywood. The results showed
that one of the most durable adhesives was the epoxy,
which even outperformed phenol-resorcinol-formaldehyde
(PRF) and PF adhesives (6). "

With the success of epoxy/timber boats of all sizes - it does seem that the older ASTM tests and the older Forest labs statements were quite out of whack with actual experience.

In every case experience should be the basis of science and it seems the Forest Products Lab is starting to ask something like the right questions - though it doesn't seem to have bothered to speak to any reputable boat builders yet to find out our secret! But they don't seem to far away from telling us what it is!

Best wishes to all
Michael Storer

werner

11-17-2007, 11:11 AM

Boatmik

11-17-2007, 11:37 AM

after reading the above text (link) the use of a primer like Hydroxymethyl resorcinol HMR seems to be a solution for failure of epoxy glue in some cases.Doubt if that product as a primer is already used or available to boat builders?

Howdy Werner

If you read the whole thing you will understand what is being said here.

The author says ...

"The original explanation
was that the HMR served as a chemical coupling
agent between the wood and the epoxy, but stabilization
of the wood surface by the HMR is now the more generally
accepted model (11)."

So the accepted reason now is that HMR does nothing but prevent the water getting to the timber enough to stress the join.

Note too that all water doesn't need to be excluded as in the wet plywood example I quoted above here again

"11 adhesives were tested using both exterior
exposure (up to 16 years) and the automated boil (up to
800 cycles) for Douglas-fir plywood. The results showed
that one of the most durable adhesives was the epoxy,
which even outperformed phenol-resorcinol-formaldehyde
(PRF) and PF adhesives."

16 Years and 800 cycles of boiling.

The article is discussing a mechanism for the failure and it is suggesting that if you remove the mechanism then the epoxy can be a very good adhesive indeed.

Epoxy/timber boatbuilding is very specific about removing that particular mechanism.

The text also points out that the original tests that gave epoxy a bad reputation don't "hold water" if you will pardon the pun as far as reflecting the real situation.

Best wishes
Michael

Boatmik

11-17-2007, 11:52 AM

Botecote epoxy washes up in warm water.
Of course if your joinery is up to the task then use Resorcinol, I would.
I also agree with using fastenings, nothing wrong with the belt and braces approach.

Sorry WX

You have got your products confused.

The bote cote epoxy certainly doesn't wash up in warm water, I've been using it for 20 years (including providing technical support)...

AND I REALLY WISH IT DID!!!!

They have a water based polyurethane paint that does wash in warm water however.

Same technology that has was originally developed for high end cars to prevent solvents getting into the environment and is starting to be commonplace in large scale painting applications.

Best wishes
Michael

werner

11-18-2007, 08:14 AM

for those still interested
http://www.treesearch.fs.fed.us/pubs/27037
If you read this publication
using a primer could be a good idea in some (stressed) constructions but then using this could be to complicated for the amateur .
At least none of the scientists finds an ugly truth.

Boatmik

11-18-2007, 09:10 AM

Howdy Werner,

A good find!

It does go into more detail in some areas.

Both articles were prepared by the same fellow - Frihart, the new one with a co-publisher. Both were published at the same time in the same collection of papers, by the look.

The main thrust of this one is to allow the epoxy to pass particular ASTM tests, in this case with the use of primers.

Whereas the other one calls into question the relevance and appropriateness of particular ASTM tests when, as the author notes, the overwhelming evidence of experience is that epoxy is a successful boatbuilding medium.

Probably the other big area of difference between the articles (and for us) is that some degree of wetting seems to be tolerable as evidenced with the plywood bonding example. From this it would appear that it is the degree of swelling/movement that makes the difference rather than the simple presence of water in the timber.

The results showed
that one of the most durable adhesives was the epoxy,
which even outperformed phenol-resorcinol-formaldehyde
(PRF) and PF adhesives. Frihart (2005)

In that case I would assume there was rather a lot of water (800 cycles of boiling) but swelling was restricted as the substrates were ply, where the cross grain of the different veneers was stabilising the timber dimension.

This is also the mechanism put forward in the use of primers.

In well conceived epoxy/wood boat building it is acheived in another way without resorting to a second product.

At any rate I would be betting money that Mr Frihart is the one to watch as far as more research in this area!

Best wishes
Michael

Tom Lathrop

11-18-2007, 10:46 AM

Hi Michael,

Thanks for your recent inputs. That helps put a cap on this thread which was degenerating a bit. In reading the original tests that FPL made, I thought that if you soaked your timber boat in water for a long time and then placed it in an oven at high temperature to dry the wood at such a rapid rate that the wood split and deformed, the epoxy joint would surely fail. Duh?:(

Strange that that is essentially what they did on a small scale for a presumably "objective" test. I have put a lot of faith in FPL but that did not seem at all reasonable. In the end I will trust my own 40 or so years experience and that of many others with epoxy in plywood boats.:)

Boatmik

11-18-2007, 11:01 AM

I'm just pleased that my web searching skills were able to locate that article and that the boffins are doing such a fine job of unravelling the truth.

Not really anything I did - I seem to spend my life using other peoples' good ideas! I certainly have none of my own.

Best wishes
Michael

erster

11-18-2007, 11:28 AM

So now what do the experts say and where do they stand with the studies of glues and adhesives when using popsicle sitcks for boats? I am so confused now that I may never be able to go out in the water ever again .;):p

allananicol

11-18-2007, 04:38 PM

pcford

11-18-2007, 04:49 PM

Simple solution is DO NOT BOIL YOUR BOAT, especially if you have used epoxy as the glue medium...........not even for one cycle let alone 800.

I for one would have trouble finding a pot big enough, so the argument is moot.......................

Do you actually think that the people that set up the test actually expect you to sail your boat in a hot spring at Yellowstone?

There is a reason for the boiling test. As I understand it, (and others may correct me) the reason in the testing protocol is to simulate the effects of the passage of time.

I suspect that the person designing the test may not believe you are going to sail your boat in a huge cauldron.

allananicol

11-18-2007, 05:25 PM

"Do you actually think that the people that set up the test actually expect you to sail your boat in a hot spring at Yellowstone?" They might 'cept I dont live there.......but someone else might like to try and let us know......;)

"There is a reason for the boiling test. As I understand it, (and others may correct me) the reason in the testing protocol is to simulate the effects of the passage of time." Absolutely correct, but I prefer the old way....it just takes time, AND you dont have to find a big pot, - er cauldron.

"I suspect that the person designing the test may not believe you are going to sail your boat in a huge cauldron." OOOhhhh, I dont know, ....you know these theoretical lab people get some funny ideas.....:D

ROFL.... I've read the full posts a couple of times to get a handle on the whys and wheretofors, but I just seem to end up greatly amused by it all.:)

There are knee jerk reactions, and considered replies. I have no doubt that the testers were good intentioned, and the results valid, but real life experiences counter the test results. I've used resorcinal, but not for years, and epoxy extensivly, with NO PROBLEMS, so the arguments to me are moot, and as for the passage of time, I am sure my boat will still be going long after I am gone, knock on wood, that it doesn't suffer a catastrophic grounding or fire.

I think that epoxy is just like any other adhesive, for example flour and water, if you mix it wrong, and use it in the wrong application it is going to fail, its just a matter of applied force and time.

Anyhow enjoyable post, and some good information and real world examples, just needed some silliness so we can move it on to the bilge and get some more ideas about the best way of cooking actual boats instead of test patches.:p

Boatmik

11-18-2007, 05:28 PM

Howdy pcford and allananicol,

The information seems to be that you can boil your epoxy timber boat providing you take some precautions or if it is built of plywood!

But please, please, please stop at 800 cycles!!!!!

But more seriously, to purpose of a test is to be convenient and repeatable. If you can do it in a day or two with modest equipment that is a great benefit.

The idea is to find something that is a bit tougher than the real life situation. Then if the item survives that then it will be OK in real service. As simple as the boil test is there has been countless hours of research to check the correlation between its results and real life results.

However, the risk is that there may by little or no relationship between what the test checks and why the item fails (or as in this case - why it does not).

And that is what the testers have to be open to. That if there is a departure between the test results and real life then the test has to be updated if the real life scenario has any relationship to what the tests are used for.

So if the particular ASTM tests are being used to see how to laminate timber railway sleepers or bridgeworks then they may make a lot more sense.

When their predictive power falls apart in a particular area - wood/epoxy boatbuilding - then they shouldn't be used or need to be revised or updated.

The two FPA papers above are a good example of exactly that. One tries to find a way that epoxy can pass the ASTM testing as it stands,
The other one says that the ASTM test methods is flawed for a particular application.
So the testing procedures have to be updated as the science gets better. Also when things don't turn out the way you expect there is an opportunity to develop new understandings and new technologies.

Best wishes

erster

11-18-2007, 05:49 PM

I wish I could get an answer about what glue I should use and expected results when gluing up popsicle sticks for the marine enviroment. I am beginning to feel like I am invisible to the outside world.:p
I keep doing the same thing over and over expecting a different result. As of yet the results are the same when I use the flawed epoxy glue.

http://img.photobucket.com/albums/v356/Bateau1/DSC03496.jpg

Watch out for "Duclin" exploding when you least expect it.

I try not to wonder too far from the shore Tom in Duclin'. Its bad enough to be in a bastardized design and hull. But to worry about the glue too, GEEEZZZ, this is getting to be too much for an old guys' heart.

http://img.photobucket.com/albums/v356/Bateau1/DSC03336.jpg

Allananicol does this reply make this thread now qualify for the bilge? :D

allananicol

11-18-2007, 06:20 PM

Erster, I dont know, not quite there yet, but if I was building a popsical stick boat I wouldn't go past Tarzans Grip. But I still wouldn't boil it.....

Boatmik, thanks for the advice on boiling, I wont go past 800, but I got to find that Cauldron first...

P.L.Lenihan

11-18-2007, 10:51 PM

Re post 65;Michael,aka Boatmik, FYI, Mr. Greer is quoting me in post 62.;)

So, it is becoming clear that some of the tests presented may not be totally accurate in guaging epoxy for boat building work. Two different boat building techniques,each with credible real world use but markedly different building methods

Thus,what is perhaps needed now is a full and proper description of HOW to properly build boats with epoxy in order to avoid failures,whose real cause is not fully understood.Yes, most of this information is available through the Gougeon Brothers manual,System Three etc....

With Mike "ersters' " considerable real world experience,along with Tom Lathrop's etc.... posting here, it would perhaps be most instructive for those new to epoxy building to read( or be reminded) of what really has to be paid attention to when building their dream boat with epoxy glue.

To begin, it is clear that your lumber must be reasonably dry stock, as per Mr.Smalser. The wood then has to be well saturated or at the very least, protected from raw exposure to water once assembled on board the boat to mitigate the cyclic swelling and shrinking of the wood. Mechanical fastenings may also be a plus in areas where one can expect considerable shock loadings.....the so called belt and suspenders approach. My own humble suggestion,which I use and have used on past boats, is to create a hollow or slight dishing on the faying surfaces, to maintain a gap for the product(epoxy) to remain in the glue seam despite the considerable pressures which may be brought to bear on the joint during assembly,whether via screws/bolts or lots of clamps, and would otherwise create wonderful potential for a glue starved joint.

Other tips welcomed :)

No reason for this thread to end up in the bilge, it just may turn into a"tutorial" for epoxy boat building which can only be a plus if it results in more folks building long lasting "failure-proof" boats out of wood:)
Keep a good thought !

Peter

pipefitter

11-18-2007, 11:16 PM

Great looking hulls, Erster. Nice to see the 22 out in the open. Looks 100x better with the full view if that's possible.

Supposedly, constant immersion of lams made with epoxy is better suited for micro lams. Thinner veneers that are more thoroughly permeated by the epoxy and less tension on the cumulative glue lines. I recall in some instances the veneers becoming nearly transparent with epoxy saturation depending on the permeability of the wood and in many cases, certain species of wood selected for that reason.

In such, some builders trying to add redundancy of lams made of stand alone rot resistant woods that may not be the best for such a situation. A lam of thin veneers of D-fir, even though not as rot resistant as white oak perhaps, would still be a better wood for an epoxy glue lam. Sometimes, one can have the best of both worlds with perhaps H.mahogany but it seems to become moot once the glue has failed enough in which the rot resistance of the wood is needed beyond that. I see many instances here where it seems folks are doing molded lams with the thickest veneers they can get away with having to torture them into super structure molds in which to save a little wood. Also, squeezing out more of the adhesive in the case of bentwood lams at their centers as they try to bend. Now the wood has stress built into the possibly starved glue lines where with thinner veneers, would have made a relaxed more consistent glue line while gaining strength by default of the buildup of the layers.

There was some rules IIRC to be followed with certain lamination processes. Shaved veneers were better built using odd numbers of layers. Slab lams made of flat sawn boards were best made of even numbers in which to evenly alternate the grains as a couple examples. When many folks build fastener free, glued hulls, I don't think they follow all the rules all of the time. In cases where one can't, it best to rely on the belt/suspender approach and include fasteners,drifts or dowels on an opposing bias across glue lines of heavier timber glue ups.

The stem of my Simmons is made of 3 flat sawn boards. I could have ripped them down into 4 parts to the rule but the stem on the Simmons will most likely never see water, has 3" screws through the plank ends crossing the glue lines on opposing angles and is epoxied and sealed well.

Edited to add: I see where P. Lenihan was saying much of the same. Sorry for repeating but I already typed it so I'm not removing it. :)

epoxyboy

11-19-2007, 12:41 AM

I guess if some of you gentlemen hold such a low opinion of epoxy, you'd best not hop into a modern Boeing or Airbus. All that epoxy holding the carbon fibre together might let go at an inconvenient moment when it detects an unbeliever on board :-)
There must be millions of plywood/epoxy structures worldwide that hold together just fine for many years. I believe most of the problems that occur are either due to operator error (eg not wetting out the joint a few minutes before clamping etc), or an inappropriate application such as some idiot trying to lock up an inherently flexible structure like an old damp "classically" constructed boat.
Given that many laminated components are curved, and by default subject to high clamping pressures when assembled, it is likely that most of the epoxy is squeezed out. Maybe that is the reason for the failure of some of these assemblies ??
It aint the only product out there, but for now it is very compatible with my level of "skill" - in other words, my joints have gaps too big to work well with resourcinol, but about perfect for epoxy.

Pete

Pete

P.L.Lenihan

11-19-2007, 03:42 AM

Edited to add: I see where P. Lenihan was saying much of the same. Sorry for repeating but I already typed it so I'm not removing it. :)

Pipefitter, I wouldn't remove it either, and not just because you think you're are repeating something I wrote but, more importantly, because it contains good tips to use when doing a laminate build up such as going with thinner boards when doing a stem etc ....thank you! :)

Peter

P.L.Lenihan

11-19-2007, 03:53 AM

I believe most of the problems that occur are either due to operator error (eg not wetting out the joint a few minutes before clamping etc), or an inappropriate application such as some idiot trying to lock up an inherently flexible structure like an old damp "classically" constructed boat.
Given that many laminated components are curved, and by default subject to high clamping pressures when assembled, it is likely that most of the epoxy is squeezed out. Maybe that is the reason for the failure of some of these assemblies ??
Pete

Peter Epoxyboy,
I happen to think pretty much along the same lines and thus appreciate your tip of pre-wetting a few minutes before assembling.With enough real world tips,from actual builders, perhaps we epoxy users may help reduce the number of "operator errors" and disgruntled builders. Some of the tips may already be published, as I previously mentioned, but a nice resumé of "how to tips" may be worth the effort if it encourages better builds :)
Thanks!

peter

Boatmik

11-19-2007, 11:50 AM

Howdy,

In conjunction with the posts immediately above ... from this point on it becomes quite a normal discussion on how to build epoxy boats.

I'm not a great fan of belt and braces approaches, there is a lot of information about good joint design using combinations of timber/epoxy fillets/glass and not necessarily any fastenings at all.

In the end wearing both belt and braces can run the risk of making one look just a little foolish in polite company.

And there are weaknesses that fastenings introduce into the structure.

For example...
Fastenings will go through glue lines which otherwise may be able to prevent water passing through if there is damage to the structure.
Fastenings have a different co-efficient of thermal expansion so can end up dimpling or cracking the surface coating or paint
Fastenings make repairs a lot more complex in an epoxy boat - one of the advantages is that you can remove substantial parts of boat with high speed cutting tools like powerplanes and routers without the risk of hitting something hard. http://www.storerboatplans.com/Faq/fastrepair.htmlIn addition there has been a lot of experience now in building boats without fastenings - no one seems to worry that fibreglass boats don't have them and that everything is just tabbed in with glass for example.

WEST, Bote Cote (in Australia) and others give quite clear guidance as to the sizes of timber, fillets, scarfs and buttstraps to hold a structure together.

At any rate it is not hard to do a bit of empirical testing oneself by making some test pieces and gluing them up - and test to destruction after. We used to do exactly this as a gimmick at boat shows. Fillet two pieces of ply together and then cut them into smaller sample pieces. Ask a doubting punter to break - inevitably impressed when the plywood breaks adjacent to the fillet .... same method can be used to check if planned methods are adequate.

There is no point in going further than the point where the timber or plywood will fail adjacent to the joint.

Also those designers that have been using the fastenerless approach have done our homework (for the most part) and have had no problems with boats up to quite large sizes.

One thing I would point out is a place where fasteners are useful. Generally where you are gluing a gunwale or bottom skid - both pieces of timber that generally are glued on only one of the possible four surfaces. When external to the hull skin there is some chance of them suffering impact with the result that a split can propogate down their length. So often I will specify a fitting at each end to prevent a split starting. Seems to work quite well.

This is rather unlikely to happen with a piece of timber glued to plywood or a glassed timber hull skin on two surfaces - the ply and/or glass would act as a crack stopper.

There are a lot of articles dealing with these areas on my FAQ, which may be useful to some.

It also details some of the tricks like temporary fastening with reusable drywall/plasterboard screws which come out of the structure at the end.
http://www.storerboatplans.com/Faq/faqindex.html

AAAAALSO, while I'm in the business of tidying up loose ends ...
WEST used to stand for
WOOD EPOXY SATURATION TECHNIQUE
But sometime people started to realise that the epoxy didn't go in deep but was still providing reliable structures.

So they relabelled it at some stage ...
WOOD EPOXY STABILISATION TECHNIQUE

Which is somewhat more accurate.

Having epoxy that "soaks in" through adding thinners is one of the myths that plagues well-conceived wood/epoxy boatbuilding.

Basically if you add thinners the end result is that as they evaporate they leave holes in the matrix thus making it quite permeable to water (http://www.storerboatplans.com/Faq/Saltpreservative2.html). The end result is that there is timber movement ... and as we have seen the epoxy joins are considerably weakened. The whole epoxy method involves the STABILISATION of the timber by not allowing much moisture in or out.

A secondary effect of course is if the water content can be kept down, then rot is very unlikely.

A tertiary effect is that the timber surface is stabilised with the result that the paint and/or varnish that is used lasts a lot longer.

This photo is of a boat that was built 13 years ago and never been repainted or revarnished. It has been stored outside for considerable periods with a cover over the top, but often collected water which might have remained pooled inside for a few weeks - maybe a month at a time. As you can see the boat is in excellent condition. It has been sailed a lot as well. There is an interesting phenomenon on the cockpit floor where the water pooled. It has soaked through the varnish but stopped at the epoxy. And you can see fungal growth between the two. Much better it is on top of the epoxy rather than in the timber!!

http://farm1.static.flickr.com/144/379091135_dac1a798cd.jpg
http://www.flickr.com/photos/boatmik/379091135/in/set-72157594516743453/

Hope this provides a quick orientation.

Best wishes
MIK

Nicholas Carey

11-19-2007, 12:16 PM

JimD

11-19-2007, 01:37 PM

I'm going to The Bilge to start a thread on the ugly truth about ugly.

P.L.Lenihan

11-19-2007, 01:43 PM

I'm going to The Bilge to start a thread on the ugly truth about ugly.

Oh Jesus,Mary and Joseph JimD, don't do that......it'll turn into something like the good,the bad and the ugly and how my girlfriend's prettier then your dog :)

Peter

johnnyv

11-19-2007, 03:16 PM

One thing to consider regarding the applicability of boil testing epoxy laminations/joints is this...

Epoxy's heat deflection temperature is c. 140 F (60 C) and its glass transition temperature is in the neighborhood of 160 F (72 C) -- boil testing an epoxy lamination -- 212 F (100 C) -- might just be predestined to failure. Especially given that the test isn't designed to simulate "real-world" conditions, it's designed as an accelerated aging test.

Don't boil yer boat :D as has been said.

Epoxy heat deformation and glass transition temperatures vary between formulation and the specific curing conditions, oven cure gives higher values then room temperature cure unsurprisingly.

Accelerated testing is often of little value when used with new polymer systems but is often usefull when testing different formulations of similar chemistry.
The boil test is good for testing your version of a phenol-formaldehyde resin for instance.
I have seen negative correlation in some accelerated salt spray tests for metal coatings and failures in QUV tests of coatings where real world performance is exceptional.

Boatmik

11-19-2007, 04:45 PM

One thing to consider regarding the applicability of boil testing epoxy laminations/joints is this...

Epoxy's heat deflection temperature is c. 140 F (60 C) and its glass transition temperature is in the neighborhood of 160 F (72 C) -- boil testing an epoxy lamination -- 212 F (100 C) -- might just be predestined to failure. Especially given that the test isn't designed to simulate "real-world" conditions, it's designed as an accelerated aging test.

Don't boil yer boat :D as has been said.

True enough!

There is a non structural issue that affects dark coloured boats in more tropical regions - after a few years you may start to be able to see a little "print through" like effect at the glue joins. A tiny bit of movement that allows you to see every join in the paintwork.

It is a cosmetic issue, but I do recommend boats that are kept in the sun be painted light colours in hotter regions. Makes a huge difference to the temperature.

Painting traditionally built boats dark colours can have much more serious effects as planks dry out above the waterline on a mooring or the whole boat dries out on the trailer.

To keep away from dark colours and red is a good idea.

Best wishes

Michael

Nicholas Carey

11-19-2007, 06:38 PM

Epoxy heat deformation and glass transition temperatures vary between formulation and the specific curing conditions, oven cure gives higher values then room temperature cure unsurprisingly.True enough. I'm going on System Three's published data and on what, once upon a long time ago now, System Three's founder/CEO, Kern Hendricks, told me. He's a chemical engineer. I suspect he knows whereof he speaks.

But the variability is I couched my numbers with terms like "circa" and "in the neighborhood of".

One other thing regarding epoxy usage. Consider how your shop is heated. From an old post of Kern H's (http://www.bearmountainboats.com/phpbb2/viewtopic.php?t=2208&view=next&sid=d0ef3a8b425b0a2da945958eb160bb03):
Direct fired kerosene and propane to a much lessor exent give off as products of combustion water, carbon dioxide and unburned hydrocarbons which in
combination can react with curing epoxy to form an unbondable surface.

Better to find another source of heat.I'd probably suspect other fossil fuels of having the same issues.

[edited to note: I just found the original thread in rec.aviation.homebuilt whence this came]

http://yarchive.net/air/epoxy.html

Some tidbits...

Kern H's original post:
Tom Anderson <nc_native@my-deja.com> wrote:

> There's a difference, my friend. I can work all day long in my garage in
> 35-50 degree temps., particularly if I've got a little kerosene heater
> keeping my buns warm. But, for epoxy to cure properly, it's important to
> keep the temp. up around 50 or so (the warmer, the better) throughout
> the cure. That means overnight and for the next 48 hours or so.
> I can deal with cold tools and fingers...but NOT a delamination at
> 10,000 feet!

And, my friend, if you are using a direct fired kerosene heater to keep your
epoxy warm during cure you may have that delamination at 10,000 feet anyway!

Direct fired kerosene and propane to a much lessor exent give off as products
of combustion water, carbon dioxide and unburned hydrocarbons which in
combination can react with curing epoxy to form an unbondable surface.[/quote]

Better to find another source of heat.

And some more detail from another post in the the same thread:
Greg Piney <gpiney@my-deja.com>:
>With NG there is no residue to end up on your project. <

Except, of course, the products of combustion, carbon dioxide and water vapor,
which in combination form a weak acid. Since curing epoxy contains alkaline
amines it will react with the carbon dioxide in the presence of moisture to
form amine carbamates and carbonates. These may affect secondary bonding or
they may not depending upon the particular epoxy formulation. I'd check to be
sure before giving NG a clean bill of health in this regard.

W. Kern Hendricks
System Three Resins, Inc.
Seattle, WA

Boatmik

11-20-2007, 12:58 AM

I didn't say it was always necessary or that a boat can't be built without fasteners.

I didn't say you did - I was actually referring to some themes of the discussion around page ... um ... two.

And just wanted to bring the other option into highlight as well as giving a rationale for the decision one way or another.

In the end people build the boat the way they do for mostly emotional reasons. They do what it takes to make themselves feel satisfied and relaxed.

The mix up occurs when people think there is only one way despite all the evidence.

I just wanted to bring in the no fastener option so it would be part of the thread. So thanks for giving me a chance to re-emphasise it as an option! :-)

Best wishes
Michael

pipefitter

11-20-2007, 01:08 AM

I didn't say you did - I was actually referring to some themes of the discussion around page ... um ... two.

And just wanted to bring the other option into highlight as well as giving a rationale for the decision one way or another.

In the end people build the boat the way they do for mostly emotional reasons. They do what it takes to make themselves feel satisfied and relaxed.

The mix up occurs when people think there is only one way despite all the evidence.

I just wanted to bring in the no fastener option so it would be part of the thread. So thanks for giving me a chance to re-emphasise it as an option! :-)

Best wishes
Michael

It wasn't meant to be abrasive. It was a just in case. One of those things hard to be put forth in text on the internet at times without sounding contrary. Appreciate the input at any rate. :)

JimD

11-20-2007, 01:10 AM

I get emotional about fasteners. But smells are strong memory and emotion triggers, too. The bouquet of freshy mixed epoxy always reminds me of happy times.

Boatmik

11-20-2007, 01:33 AM

And JimD,

That is exactly what it is about!!!

I don't think I would go quite as far as you in saying epoxy has a .... a .... bouquet!

But when I finish the job it looks right - to my standards - I think it is hugely satisfying and I know that I can trust the structure.

http://farm3.static.flickr.com/2329/1717093412_b0f5b6c32d_m.jpg
http://www.flickr.com/photos/boatmik/1717093412/

http://farm3.static.flickr.com/2288/1599911441_c3bb83a014.jpg

And it is time to get on the water!!!

A happy time indeed!

Best wishes
MIK

Wild Wassa

11-20-2007, 01:48 AM

Epoxy is child's play. Epoxy isn't ugly, I make interesting things out of epoxy. I make laminates that I couldn't make without epoxy somewhere in the system. Make Epoxy work for you ... don't be a self fullfilled victim to Epoxy.

F'n fasteners are certainly the bane of my life ... they have the better of me on every occassion. Fasteners are f'ugly. I wish I understood fasteners. Maybe in about several thousand more bedded fasteners from now something might click ... but I doubt it.

Fasteners are ugly ... epoxy is beautiful.

Warren.

JimD

11-20-2007, 02:00 AM

Warren, perhaps a new thread 'The Ugly Truth About Fasteners' is in the offing? :D

P.L.Lenihan

11-20-2007, 02:03 AM

Warren, perhaps a new thread 'The Ugly Truth About Fasteners' is in the offing? :D

NOOOOOOOOOOOOOOOOO! Please JimD, for the sake of the Blessed Virginwannabe St.Paris,don't do it......at least not while I'm at work...:D

JimD

11-20-2007, 02:13 AM

Warning: Graphic Image! Not for the squeemish or easily offended! I ruddy well mean it! This is one rusty fastener: http://www.yachtsurvey.com/ScrewRusty.jpg

The above photo is from the following marine survey website: www.yachtsurvey.com (http://www.yachtsurvey.com/)

Wild Wassa

11-20-2007, 02:14 AM

Jim, I think that I'm a fastener dyslexic.

PLL, you will just have to sit there and bare it, keep working Skipper.

I have fastener charts that have their own fastener charts. I have fastener templates that equate fasteners in imperial sizes to fasteners in gram weights that equate to alternative fasteners in metric sizes and when I know exactly what fastener it is that I want in what particular grade and obscure thread type exactly ... 'Specialty Fasteners' the retail gods of fasteners ... have that size and grade in stock but the guy who is the specialist in obscure thread types and who knows which shelf they are at the back of is having the day off ... then things always seem to get really ugly.

Yes I think a thread about the ugly truth about fasteners is very appropriate and way over due.

The guy who invented the hex nut should have been tried for crimes against humanity ... and that bast*rd who invented the shifting spanner, he was in on it too because he collaborated with the dude who invented the imposible space to get into to remove a hex nut.

The guys who say, "316 in a 1/2" bolt? You can't get to it? just drill it out." ... yeah right! ... let's hold these dudes to account as well.

The person who invented the rivet, a true wonder of engineering ... was obviously not the idiot who invented the hand held rivet gun.

Scrape the surface of fasteners and the uglynes is all pervasive. After you have fought with fasteners ... epoxy is a joy to return to and one of life's simple pleasures to use.

Warren.

JimD

11-20-2007, 02:32 AM

Warren, since its confession time I have to admit I've stripped the heads off more than one bronze screw. Really tough to get them out once you've done that. Once I made such a mess trying to get one out I had to cut around it using one of these:

http://www.holesaws.com.cn/products/holesaws/bimetal/pic/holesaw.jpg

and then plugging the hole with a big bung! Boy, that was a job!

P.L.Lenihan

11-20-2007, 02:51 AM

and then plugging the hole with a big bung!

Quit yer braggin' JimD, Paris ain't gonna come runnin' any faster if you start scaring her off like that :D

Now go and start that thread about fasteners,why dontcha.Oh,by the way, I'd like to see the guy who invented the machine that copies, just a C-hair off, the true Robertson drive screw,kept on a steady diet of prune juice for a month,in the woods,with no arse wipe.........Bastid!!

Peter

JimD

11-20-2007, 02:59 AM

....kept on a steady diet of prune juice for a month,in the woods...

Peter

It should have to be a coniferous forest so there were only pine needles available.

werner

11-20-2007, 05:00 AM

MiddleAgesMan

11-20-2007, 06:12 AM

That's just Ruele(sp?) Parker's justification for taking the easy way out. Just because he said shock loads have been known to shatter epoxy joints doesn't make it true.

A shock load might cause a poor joint to fail but it won't do the same for a proper epoxy joint.

In that same article he admits to assembling parts with a staple gun, embedding the staples and covering them with filler. Reading that confirmed my first impression when I went on board one of his early boats--he's a down and dirty builder who has found ways to justify his poor methods.

P.L.Lenihan

11-20-2007, 06:44 AM

Within the context of the most recent article, he(Parker) does mention working to a rather narrow or tight budget as layed out by the client.Time was also a pressing issue as the"shop" was slated for demolition within six weeks or so. Would an open ended budget have changed his methods? More time?

Peter

JimD

11-20-2007, 07:12 AM

How much money ya got? I can build as cheap as you like. :D

Tom Lathrop

11-20-2007, 07:35 AM

just happen to read the article in the latest wooden boat nov/dec page 39
quote"I firmly believe in leaving all fastenings in place, as "shock loads" are known to shatter even large epoxy glue joints and fillets" unquote (of course read in context of the article)
that's a boats builders statement based on a well thought over choice but of course I think in this case it is easier to leave the fasteners in.

Undoubtedly true. What is not said is that shock loads can shatter any joint, glued, nailed, screwed or welded in any combination. Once saw a demonstration by Sam Devlin in which in which a sledge was taken to chine joints done with epoxy/glass/filet and chine log/glue/screws. Guess which one failed first.

I thought about how that could be for a while and came to the conclusion that the chine log creates point loads at the edges of the log where stress is very high. An epoxy/glass/filet joint spreads the load out and distributes the stress better to absorb the shock. Other thoughts?

Of course, these were isolated sample joints and in a real boat, there would be other strength members that affect the situation. Either kind of joint has proven to be effective over the years so the point may be moot anyway.

Dave Hadfield

11-20-2007, 09:21 AM

I think part of the de-lamination problem is often caused simply by amine blush. This is hardly breaking news, but I do believe people tend to take a shortcut, and don't remove this.

Some epoxies are worse than others, but if you let a layer cure, it often exudes an ammonia-like layer. This should be washed off. The temptatation is to only sand it. This kind of smears the stuff around. It interferes with the bonding of the next coat. Far better to wash it off. The blush is quite water soluable.

I was quite surprised once, covering a canoe, to see the sheer quantity of crap that ended up on my wet rag -- this from a gleaming, apparently crystal-clean hull.

The better alternative is to keep the layers going on before the epoxy has a chance to completely cure. More of a chemical across-the-layer bond this way.

Anyway, sorry if I'm telling everyone what they already know.

The other thing about epoxy is that it's no fun. Sure, you can attach a large piece quickly, and that's pleasant, but it's just googe. Smells bad, it's toxic, drippy, gooey.... It's not exactly planing a shaving off a long clear pine board. I like to enjoy the building of the boat -- the act itself.

My last few several small boats have been plywood, using squeeze-tube Bulldog Premium (polyurethane) adhesive, with screws or ringed nails. Frankly, I like that more. Cheaper, too.

As for the resourcinol, the masts on Drake (46 ft wooden ketch) are Sitka, over 60 years old, and show zero trace of delamination. Pretty good record, I think.

willmarsh3

11-20-2007, 02:49 PM

I just saw this:

http://www.landlpardey.com/Tips/2007/April.html

The temperatures he quotes seem a bit low. During the summer here it can easily get that high for an item sitting in the sun or a hot storage shed. I havn't had any problems yet.

jlapratt

11-20-2007, 05:47 PM

"..... we are uncomfortable about using epoxy adhesives for any structural members of a wooden boat or for any wood to wood gluing where the joint will be subjected to either heat, regular soaking in water, and what is called deep cycling, i.e. being wet then dry, time and again, or exposure to UV light. .....all have low Heat Deflection Temperatures. HTD is the temperature at which any plastic (epoxy is a plastic) will soften enough to loose 30% of its strength. ....request that in future we capitalize the name West System and if possible use the trademark symbol. I.e. they could not refute any of the problems we stated. "

More spin, I'm afraid. ASTM D 648 ISO 75 doesn't mention "30%" decrease in strength.

As many others have said, don't epoxy thick laminates that run through wet-dry cycles. Or expose epoxy to excessively high temperatures (like boiling :D)

Just because the lawyers requested trademark protections and didn't "refute any problems" doesn't mean you can jump to the conclusion that the "conclusions" reached are valid.

Jeff

paladin

11-20-2007, 08:53 PM

I know that the formulations of the epoxy used by the Gudge Bros. has been changed at least 3 times since the start of the business. I used their epoxy in an early project, a 12 1/2 foot power boat that was built at English Harbor. I had a nice tent with a dehumidifier and an airconditioner to work with and the temps were in the 75 degree range. All the work and joints went well. But just under a year later the resin started "crystalizing" and crazing and then eventually one evening, the owner was leaning against a panel and the joint just gave way. Several other boats that used the W.E.S.T. resins were having the same problems. The next boat that I built using the same system used T-88. I have never had problems with T-88, However....more recent studies would indicate T-88 be used for all structural work, but for fabric coverings on wood panels, the M.A.S. epoxies may have an advantage

Boatmik

11-21-2007, 04:52 AM

Howdy All,

As far as choice of epoxy...

My feeling is that work methods are much more important than epoxy choice.

There is one important caveat on that.

A few years ago (hmmm a decade now) there was a series of tests done on most of the common types of epoxy available at the time by one of the universities here.

The three best known and most expensive in Australia were head and shoulders above the rest on every test. One would have a bit of an advantage in one area or another - one of the others would have a bit in another.

WEST was one of them. I have links to the other top performing one - a competitor (just so you are clear on my biases). I would have no qualms about building a boat of WEST.

The other lesser known and cheaper epoxies clumped together WAAAAAY down the list - on every measure. I don't mean a difference of 5 or 10% - more like 50 or 60%.

The graphs were just startling.

One of the ways that epoxies are sometimes made cheaper is to add a solvent to "bulk it out" a bit. This reduces the mechanical properties and water resistance a lot.

Good quality epoxies are "high solids" with a minimum amount of thinners used in the production.

Luckily it is generally possible to smell added thinners - epoxy, particularly the hardener should only ever smell slightly of ammonia.

There are other ways of reducing quality and price besides adding thinners. I would strongly recommend sticking with (!!!) well known quality brands. If you haven't heard of it before or it isn't intended for boat building ... I would steer around it.

Same goes for joint engineering. Designers with track record should be the guideline for construction details --- or if in doubt glue up a section and test it. Remember though that a joint does not necessarily carry the whole load - there may be internal structure like seats and cabinetry in modern epoxy constructed boats that are sharing considerable amounts of the load across any particular joint.

Which moves on to more general engineering issues.

Best wishes
Michael Storer

Boatmik

11-21-2007, 05:27 AM

More spin, I'm afraid. ASTM D 648 ISO 75 doesn't mention "30%" decrease in strength.

SNIP

Just because the lawyers requested trademark protections and didn't "refute any problems" doesn't mean you can jump to the conclusion that the "conclusions" reached are valid.
Jeff

Quite right Jeff.

And I think that "Spin" is almost excessively polite of you! :-)

As we saw before in this thread there are people who would rather feel that "they are RIGHT" than look at data in any way objectively.

The reason that the forest products lab started questioning the results of its tests is because...

1/ their tests indicated that epoxy would fail in a wet environment

2/ that wood/epoxy boatbuilding is successful

They can see the conflict in those two statements and see which side the weak link probably lies on - their job is to be objective and not emotional.

Some people are able to look at data and experience in a rational way, but others will go to the grave attesting that what they wrote in 1990 is still 100% true 17 years later...

Like I said - people choose a construction medium and method for emotional reasons as much as any - and this is well and good. People can build the boat that they find emotionally satisfying whatever method or design they choose.

But when when looking at the mass of objective information out there - ie squillions of successful boats - and then still failing to update one's position ... I think "spin" doesn't come close.

The question to ask is not whether a particular method "sounds good" to us, but to objectively weigh all approaches in terms of results --- ie boats being used productively and usefully in a large enough number.

By the way - this doesn't mean at all that someone with a closed mind can't make an excellent contribution in their own area - but even within that context it is good to remember their proclivities and balance it with reading from other writers.

Now theres a good message ...
"Read More Books!"

Best wishes
Michael Storer

Boatmik

11-21-2007, 05:39 AM

JimD, Paris ain't gonna come runnin'
Peter

P.L Lenihan - you are BAAAAAAD!

You wouldn't happen to be Australian would you? Or is it just a British Commonwealth thing?

hehe

Best wishes
MIK

P.L.Lenihan

11-21-2007, 01:23 PM

You wouldn't happen to be Australian would you? Or is it just a British Commonwealth thing?
MIK

Does being Irish count? :)

Keep a good thought!
Peter

Boatmik

11-22-2007, 03:38 AM

Does being Irish count? :)

Peter

I think that's a large part of where it came from here too!!!!

Nice to meet you!

Best wishes
MIK

annerick

11-22-2007, 07:32 AM

Perhaps observed differences in long grain bond durability between some epoxies and some resorcinols under moisture induced stress can be explained in part by different thicknesses of the glue layers. A thin resorcinol glue layer may break into parallel "ribbons" when wood on both sides of the bond swells. Glue breaks, along with small wood cracks between the ribbons, might limit the shear stress between the resorcinol and the wood (and within the wood) thus preserving much of the bond integrity.

With a thicker epoxy glue layer, swelling shear stress may fail the wood to epoxy bond, or the wood, before the epoxy breaks into "ribbons".

Rick

P.L.Lenihan

11-22-2007, 10:39 PM

Interesting notion there Rick. Have you seen this ribbon effect in failed joints? I do agree that having a"thicker" glue line,within reason, can go a long way, especially if it demonstrates that there is sufficiant product,be it resorcinol or epoxy ,which has remained in the seam and not simply drawn up into the wood fibers leaving little in the actual seam line,ie;glue starved.
Thanks! :)

Peter

P.L.Lenihan

11-22-2007, 10:42 PM

I wonder if GRINGO or Steve Grube,(the original poster) has given some considered thought to his glue buying, now that many have contributed to answering his query? Gringo? Steve?

Peter

geezer

11-23-2007, 05:01 PM

I just went to pick some up and the chap in the shop said, "do you want some epoxy resin", and I said, "no, i want the best resin you have!"

Gringo

11-23-2007, 09:45 PM

Steel. I'm going to buy welding rod and build a steel boat.

P.L.Lenihan

11-23-2007, 10:29 PM

Thanks Steve. I was once dangerously close to building a steel boat until the day I had a serious talk with a pro welder and I had to conclude that,despite myself, I just did not have the necessary skills to do it right the first time nor the budget to build 2 boats. That is, the first one to learn on and perfect my new skill and the second one to keep :)

Best of luck with your choice. Any clues as to which design you're going to build? The interior will surely be made out of wood and so some pictures are always welcome along with an up-date every so often :)

All the best!

Peter

Gringo

11-24-2007, 04:50 AM

Peter, I was kidding.

I'm hopelessly devoted to wood, with or without epoxy.

This has been a very helpful thread to me. Judging from the amount of visits (approaching 4500 as I write), I'd say it was helpful and interesting to lot of people.

What it is that I think I've learned from this tremendous outpouring I can't exactly say. It will take days and weeks to really digest it. But one thing I can say with certainty is that those who frequent this forum have passion and concern for the honorable craft of boatbuilding. Only good things can come from this.

Wild Wassa

11-24-2007, 01:56 PM

"What it is that I think I've learned is ... I can't exactly say. It will take days and weeks to really digest it."

Let me save you much time, so you can start on the project ... what epoxy actually comes down to is keeping up timely and proper maintenance once it is on anything.

Selecting the right fillers to take away the brittle by nature characteristic of epoxy when it is needed structurally or to change the epoxy's characteristics for doing things like fairing or keeping it clear and non-yellowing by selecting the particular hardener for glass sheathing or select the best resin hardener combination that best suits your working conditions and climate to give the result you're looking for ... these skills only come from doing and reviewing.

Saying "epoxy is ugly" is just a smoke screen masking the real problem. The ugly truth about epoxy is what we start with, that is the real problem ... it is called wood.

In thye 12 days that this thread has been running, I've restored 3 racing dinghies and finished restoring and launched a yacht ... all thanks to the speed and ease of using epoxy. Don't take too much time to think about epoxy. Just start.

Warren.

Boatmik

11-25-2007, 09:37 PM

"Saying "epoxy is ugly" is just a smoke screen masking the real problem. The ugly truth about epoxy is what we start with, that is the real problem ... it is called wood.

Warren.

That's so simple it almost sounds wise!

Thanks Warren

MIK

P.L.Lenihan

11-25-2007, 10:44 PM

Warren has a good part of it correct.Wood is indeed important, as Mr.Smalser has already stated. I would humbly add that ones methods or techniques of actually using the stuff plays a big role too. Once you've got the wood thing down pat and the epoxy stuff mastered, your efforts will be rewarded with a truly robust craft capable of handling as much as the skipper can take:D

Just to repeat myself,a proper measuring followed by a thorough mixing of the epoxy to get started.Only add fillers and thickeners after the epoxy is thoroughly mixed. Then a slight dishing or hollowing of the faying surfaces followed by a pre-wetting of the faying surfaces. And finally, a thorough sealing or covering of the wood surfaces/epoxy(high build primers and/or paints) to protect the remaining wood surfaces from further moisture absorbtion and the dreaded cycling :)

Peter

erster

11-26-2007, 06:51 AM

Saying "epoxy is ugly" is just a smoke screen masking the real problem. The ugly truth about epoxy is what we start with, that is the real problem ... it is called wood.

I wished you would have told me earlier before I just got this beautiful stack of lumber, well seasoned, clear and have lofted a new 24 foot hull for it. I had decided after reading this thread to forgo epoxy completely. I may now have to go with steel as Gringo has suggested, wisely I guess indeed. :( Gosh he, like me has been forewarned enough that we should indeed heed the warning. Whats a guy to do now?

http://img.photobucket.com/albums/v356/Bateau1/DSC03599.jpg

Stiletto

11-26-2007, 06:45 PM

Those boards have an interesting profile, what were they originally made for?

Rob Hazard

11-26-2007, 07:55 PM

Look like window sill stock to me...

Wild Wassa

11-27-2007, 02:24 AM

I saw one ugly truth about epoxy on wood today.

I had recut a Tasar daggerboard this morning and had finished reshaping it. Tasar daggers are much longer than are needed so I cut it down to reduce the drag and I had earlier finished preserving the timber with TPRDA and I had just finished fairing one side of the board with a light weight filler in epoxy when a huge blowfly landed in the epoxy, after I had been so very careful with my fairing ... that is the ugly truth.

The blowfly also saw the ugly truth about epoxy.

Warren.

jkess777

11-27-2007, 03:53 AM

I was a stair designer and builder for years. The photo below is of a laminated stair with plywood stringers. It is a freestanding stair which could handle high loads with flexability and without failure.

http://i128.photobucket.com/albums/p163/jkess777/14.jpg

It was glued up using white wood glue and staples left inplace. Any glue used on any application can fail. And as before mentioned it has more to due with moisture content of the wood and an unclean glueing surface. In the case of oak a surface not roughed to the need of the glue.

A basic college biology class teaches us that wood has an exterior skeletal system. The outer wall of the cell allows the wood to exist long past its death as a tree. The cell then has a void which can be filled with glue and once the glue drys can hold the shape man desires to make it take and have a cell to cell bond.

When it comes to epoxy and stress failures it may also be due to light design. The use of epoxy has called for design changes which tend to be lighter than in years previous to it's emergence on the boatbuilding scene.

At any rate, failure can happen therefore the old ways of screws and other fasteners should be used along with the glue.

Epoxy is a true wood butchers dream come true.

Just an opinion.

Jim

P.L.Lenihan

11-27-2007, 04:00 AM

The blowfly also saw the ugly truth about epoxy.

Warren.

:D:D:D:D !!!

P.L.Lenihan

11-27-2007, 04:02 AM

[QUOTE=jkess777;1701631]http://i128.photobucket.com/albums/p163/jkess777/14.jpg

WOW! Wonderfully graceful design and execution Jim!!! But,I just have to ask.............does it float? :)

Peter

jkess777

11-27-2007, 04:06 AM

Peter,
Only if you threw it in the water. lol!
Jim

P.L.Lenihan

11-27-2007, 04:24 AM

Fair enough :)

But seriously, I understand now why your Light Schooner came out as nice and well put together as it did.You're a real craftman!

Peter

pipefitter

11-27-2007, 08:55 AM

Erster, I may never look at dumpster scraps and mill ends the same.

Pierce Nichols

12-05-2007, 02:23 AM

A few thoughts (from a mechanical engineer with a bit of epoxy experience):

First, the fatigue numbers quoted earlier may be true (I'm not in a position to say for sure), but they're pretty much useless, because fatigue is not in any way a linear phenomenon (quite the reverse!). Just because you lose 40% of your initial strength to fatigue in ~5 weeks doesn't mean you lose 80% in ~10 weeks. Many materials (in particular mild steels) have what's called a fatigue limit, i.e. a point at which they no longer lose additional strength to fatigue. Fatigue is a tricky subject, and I don't really want to be here all night, so let me leave it at this -- anyone talking about fatigue in simplistic terms, especially if they try to use those terms to scare you, either a) don't understand fatigue or b) are trying to sell you something. In Pardey's case, I suspect the former. Not really a slam against him -- fatigue is poorly understood anyways, and even most working engineers don't have any sort of real handle on it.

Second, joint design with epoxy is absolutely crucial. Epoxy adhesives have gobs of strength in shear, significantly less in tension, and none worth discussing in peel (imagine trying to peel two straight pieces apart and you have an idea of what that looks like). At least two of the failures pictured in the Pardey paper someone else posted a link to last page or so are pretty obvious peel failures -- the failed winch pad looks exactly like the peel failures I generated when I was first experimenting with epoxy adhesives for structural applications at work. The other is the boom caddy (I can't remember the correct term, and can't find the post on a quick scan right this instant), where the laminations have come apart at one of the cutouts for the boom. The stored spring force of the wood exerts a peel force on the joint, and there's nothing holding it together otherwise.

Third, there are quite a few boats out there built with wood-epoxy methods that have enough history to serve as an existence proof that the techniques can work. The fact that they are not working for other people would tend to indicate those other people are doing something wrong -- improper surface prep, improper epoxy mixing, improper joint design, etc. Epoxy is significantly different in behavior from traditional boatbuilding materials, and failure to properly attend to those differences will cause the vessel to fail.

Fourth -- mixing techniques (i.e. wood-epoxy with traditional) sounds like guaranteed trouble.

Fifth -- it's clear that the water boil accelerated aging (because as many have noted, that's really what it is) test is invalid for wood-epoxy composites. It's easy to see why -- accelerated aging test of all kinds (they're extremely popular for electronics reliability testing) rely on the high temperature behavior accurately modeling the normal temperature behavior, only faster. For epoxy it does not, because most epoxies used in boatbuilding change phase* (i.e. go through glass transition) at temperatures below that of boiling water. Therefore, the behavior at that temperature does not accurately model that at more normal temperatures.

* In this context, a change of phase is a change of crystal structure, not anything as dramatic as melting.