The Ugly Truth About Epoxy?

[Gringo]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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

[CK 17]

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]

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]

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]

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]

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.









Note filled countersink holes where 1/2" galvanized bolts were installed...



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/vbulleti...ighlight=Wenda

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

http://www.canoeyawl.com/

RB

[mike hanyi]

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]

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.]

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]

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

[Jay Greer]

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]

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]

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]

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/...FRquQAodkidVzA

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]

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

[Bob Smalser]

Here is basic resorcinol for $115 a gallon:

http://www.cpadhesives.com/Online_St...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.

[RodB]

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/...Cure-p101.html

http://www.chemical-supermarket.com/...stry-c150.html



RB

[Don Z.]

Here is basic resorcinol for $115 a gallon:

http://www.cpadhesives.com/Online_St...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]

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]

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]

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]

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]

... 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]

...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]

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/pd...frihart004.pdf

[Tom Lathrop]

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.

[paladin]

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]

[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

[WX]

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]

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]

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. Clean up 5200 the mineral spirits.

[WX]

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]

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]

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]

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]

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/pd...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...



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



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

[P.L.Lenihan]

[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]

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/vbulleti...ad.php?t=71208

Read the last line of Post #28.

[P.L.Lenihan]

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]

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.