New 5200 Bottom or....

[marsbar]

Lots of discussion threads on the use of 5200 for a new plank on frame bottom (beding between inner plywood/veneer and outer planks). Seems to be good history of its usefulness and longevity in this application. Many high quality restorers use this exclusively.

Also see rave reviews on PL Premium as a replacement for many uses for 5200 at a fraction of the cost. Does anyone have experience in using PL Premium for a new plank on frame bottom? It sounds like it could be an attractive alternative, providing the properties of the material are right. Must do the job "right" and don't want to risk long term performance to save a few bucks.

[Uncle Duke]

marsbar,
I will again (as usual) start by acknowledging my ignorance ("the disclaimer"). Others here will have great information.
Having said that, OSI's PL is listed as an adhesive ("PL Premium is a polyurethane adhesive...", http://www.stickwithpl.com/Products.aspx?ID=Premium-Polyurethane-Construction-Adhesive
and 3M 5200 is listed as an "adhesive/sealant" = ("stays flexible"):
http://multimedia.mmm.com/mws/mediawebserver.dyn?6666660Zjcf6lVs6EVs66SY6HCOrrrr Q-
Smarter people than me will weigh in here, but to me that says that if you use the PL, you are 'adhering' pieces together - i.e., good luck if you ever want to get them apart. If you use 5200, you may be able to get them apart. Possibly with effort, but still.....
Smart people here will post about actual long term experience, especially in terms of 5200 - i.e., "it's sealant for 'x' years and in that time period you can get stuff apart, but after 'y' years consider it an adhesive". Or something.
Do you want the planks to be removable at any point in the life-span of the boat?

[Paul Pless]

Uncle Duke,

You just can't stay out of these 3M 5200 threads can you?:D ;)

cheers,
Paul

[Uncle Duke]

Paul P notes:
You just can't stay out of these 3M 5200 threads can you?

Welll, no. In each case I defer to everyone else, suggest that there are experts, etc. Personally, I'd really like to see some end to this - some people love it, some hate it, but nobody seems to have any definitive answer. And, personally, I like to see some definitive answer before (next spring, or so) I have to make a decision on what to use. Selfish of me, sure. No problem.
Each time 5200 comes up in discussion there are people here who go offline to have duels at 10 paces. OK, that's a stretch.... but still I've been reading all the 5200 stuff here for a very long time, and it never seems to come to any conclusion.
So, until it does, I'll keep poking at smart people (like you).
Am I poking hard enough yet?

[edited to add: Paul, I'm not trying to start fights, sorry if I didn't make that clear. I'm trying to clear the playing field and learn stuff. It probably does not matter what you use, for the first 10-15 years. But I'd like to know something about the choices beyond that....]

[Paul Pless]

I know your not trying to pick fights and at this time I was only trying to be humorous. It does seem though that these threads have attracted both you and I for what ever reason. And to be fair, some of the threads have also had some rather ridiculous content as well.

Btw, Uncle Duke, what ya building?

[Rick Starr]

I've been surprised, following some of these discussions. I always thought that 5200 below the water line was frowned upon, if not outright dangerous. Did I miss something? I don't have any experience in this regard, except for a local boat which the local yard recaulked with 5200 and subsequently sunk as a result.

[marsbar]

Uncle Duke,

I agree that there seems to be no finalization of the 5200 debate. I am at a point where I need to make a decision on which way to go....5200 or other. I am sure that to remove a plank that has been married to 5200 is no plesant task. Don Danenberg simply cuts it out with a router...no way to save the plank. I'm not worried about removal of bottom planks at this point...but will deal with that when the time comes....with a heafty router ;-)

[Uncle Duke]

Paul Pless asks:
Btw, Uncle Duke, what ya building?

Paul, I don't want to divert this thread, because it's valuable, but I do want to answer your question. I'll start a new thread - but I'm not sure where. I would think "Misc...." - you're a veteran here, is that appropriate?
And... any comments on PL vs 5200?
Neil

[edited to add: Paul notes: "at this time I was only trying to be humorous". "At this time"? So, what, later you're going to rip me a new one?:D :D Not really building - rebuilding, if that makes a difference on where to post...]

[Paul Pless]

And... any comments on PL vs 5200

No real quality comments, I'm more of a boat owner/user than a builder. Most of my experience with boats is with either fiberglass or aluminum. I've often thought if there's gonna be any reason to take it apart in the future, I'd not want to have to be dealing with 5200 though.

Your best bet for advice on 5200 will be from the likes of Mike Fonville, Bob Smalser, Duoglas Noyes, and Dave Fleming I think.


I'll start a new thread - but I'm not sure where.

If its a restoration, put it up here in Building and Repair.

just as an aside on these arguementative issues of building techniques:

other than ferrocement, I'm of the opinion that there's no 'wrong way' to build a boat.

[Ross M]

The following quote is from the Late, Great "Chemist" on a thread titled "Polyurethane Adhesive as a glue?"

The Chemist's comments are oriented towards Gorilla Glue in particular, and Polyurethanes in general. One thing is clear - he did not like Isocyanates, and for good reason.

Now compare PL Premium's MSDS to 5200's MSDS.

PL Premium contains 10-15% isocyanates; 5200 contains less than 4.5% isocyanates.

If you include diisocyanates, PL Premium is at 25-40%; 5200 is less than 4.52%.

The term "Polyurethane" glue means a lot of different things, as you can see from the foregoing. that is because the guys who write the hype for these products play fast and loose with nomenclature and mostly don't know a carbonyl group from a free radical, and would not recognize a urethane linkage if it bit them on the nose. They work in Marketing. They keep their consciences in a jar in the closet.

Very simply, glue is chains of atoms with some characteristic structures along the length of it (the backbone, if you will) and some other characteristic structure (a Functional group) on the ends. After time exposed to the air, or after mixing two components, Things Happen.
Maybe water vapor or oxygen in the air is the second component, or something evaporates out of the glue, allowing Things to Happen.
The result of Things Happening is that, after Everything Has Happened, All those little molecular chains are stuck together into one big molecule about a hundred miles long with more branches and entanglements than the Interstate Highway System. Bits of molecular hair are stuck out of the Big Molecular Hairball everywhere, and they are more sticky than anything you could imagine. They stick 'most anything they touch into the Big Molecular Hairball and thus are all stuck to each other.
Some glues are very rubbery, such as 3M 5200. Some are relatively hard, such West System epoxy, Gorilla Glue or resorcinol. The hardness ahs to do with the relative length of the molecular chains this all started with, and how many Functional Groups there are on each end and maybe branches along the length. If there was only on each end one thing that could connect to one other, you can see that we would grow only longer molecular strands after Things Had Happened, and our Big Molecular Hairball would have all the cohesiveness of a plate of oiled spaghetti. The harder glues are made from relatively short chains with many branches, so as to form a rigid three-dimensional structure.
The Urethane reaction was discovered by Otto Bayer in 1938. It consisted of a hydroxyl on one end of a molecule reacting with an isocyanate on another end of another molecule to form a (I cannot exactly draw it here, but one molecular chain has a nitrogen with a hydrogen on it, the nitrogen further connected to a carbon with a double-bonded oxygen connected to it, the carbon further connected to an oxygen which was of the original hydroxyl, that further connected to whatever the original hydroxyl was connected to.) characteristic NHCOO linkage in the middle of the chain. This is a urethane linkage. A molecular chain may be made up of these here-and-there in the backbone and yet be a conventional varnish in all other respects, and some guy calls it a urethane varnish. The boss says, wait a minute, I want a name of my own. Call it Varathane. There ya go.
The urethane prepolymer chains may have silanol groups on the end, as do most commercial caulks, and these react with each other two or three times on each chain end, as well as sticking to anything else they touch. Well, it does not cure by the urethane reaction but it has some urethane in the backbone so it is called a urethane glue.
Earl Scheib, famous for his "Yeah! I'll paint any car for $99.95! And for an extra twenty dollars I'll even throw in Polyurethane! [as the guy in the backgrouhd, dressed in a chemist's lab, coat pours a clear glass cylinder of some clear liquid into a can of paint] car painting television commercials, had some other stuff. Polyurethane paint, evidently.
The urethane glue may have no urethane in it but only isocyanate-terminated molecular chains. Isocyanates react with moisture in the air to form amines, with the liberation of a molecule of carbon dioxide gas (aha!, you say...yes...but wait...) and the resulting amine reacts with two other isocyanates to form ureas (NHCONH, something like a urethane ) and the whole thing becomes the Big Molecular Hairball as these Things Happen.
The Functional Groups have a lot to do with how sticky the glues are. Isocyanate-terminated glues will react with the moisture in the air and may, if there is enough isocyanate present, show foaming when cured. No foaming is not proof of no isocyanate, but suggestive.
Small isocyanate molecules are Bad Things To Breathe. Such is in the Gorilla Glue, and maybe others, but I am not sure. Look on the label in the fine print and see if it warns that it contains isocyanates of any sort. You will need a magnifying glass to find these warnings, usually.
I will try to find the Gorilla Glue diatribe and paste it in here.
chemist
posted 03-07-2000 08:59 PM
--------------------------------------------------------------------------------
Gorilla Glue is a mixture of monomeric and polymeric (meaning three or four monomer molecules hooked together) methylene diphenyl diisocyanate (MDI). The monomer content is a critical health issue. The vapor pressure of the monomer is such that if there is more than about twenty percent monomer in this stuff, then it will exceed the safe exposure limit of fifty parts per BILLION for MDI, which is considered a VERY strong sensitizer. The ACGIH (American Council of Government and Industrial Hygenists) does research and sets these limits. You should believe them. The Gorilla glue MSDS and literature I have seen says the stuff is safe and so forth, but that is in the fully cured state only. They may not make this distinction.
MDI will bond most woods well enough for some applications, but should have tight joints. Isocyanates react with moisture to liberate carbon dioxide gas and form polyureas when reacting with themselves. The foamed polyurea may be weaker than the wood. Exterior grade plywood is made by spreading a thin film of MDI ( The Gorilla just buys this stuff in drums and repackages it) on the wood laminations and then the stack goes into a press and that goes into an autoclave where it is cured under pressure, heat, and live steam. So, for some applications it is great stuff. Used in a controlled industrial environment it yields an excellent product and the stuff is cheap to make. Personally, I would never offer such a product to the public because the permissible exposure level (PEL) is too close to what a user gets when using the product as recommended.
Go look at the label. Do they tell you to wear a gas mask with an isocyanate-rated filter cartridge and not to get it on your hands and what can happen if you do get it on your hands? Hah. I'll tell you what happens when you do get it on your moist little hands: The isocyanate reacts with the moisture to form amines, and in the presence of excess moisture some amines are left over that the other isocyanates do not find. The result of that is that you now have on your hands methylene dianiline, which is a really excellent and very efective carcinogen. The safe exposure level for that stuff is "run away at high speed".
Aside from those details, it can be a useful product. Wear gloves and keep the wind at your back.

[This message has been edited by thechemist (edited 06-12-2000).]

[sdowney717]

I use PL Premium to edge seal plywood panels, amoung other uses. works well, totally waterproof, wont harden and crack. Its an adhesive and sealer, not rubbery as 5200 but will flex somewhat. I think of it like flexible epoxy, it is really a very good glue.
Sands down nicely. Does turn yellow in sunlight.
Works well with sawdust as a filler, It will swell up and as it starts to set, you can press it back down to get rid of entrapped air bubbles.
Used on the bottom, I would imagine it would create a stiffer hull than 5200. And it wont let go. I think 5200 eventually will let go, I dont think PL Premium will.
PL premium on unsound wood with loose wood fibers will not hold. Better to use a penetrating epoxy first to soak into the wood and then you can use PL Premium. If you are using it to fill gaps, mix a fair amount of sawdust into it. It will swell up and cure thru any thickness! If you dont mix in sawdust, you are limited to a max of 3/8 inch for gaps, and I think it will loose some strength.

[marsbar]

As long as the PL would remain just slightly flexable, that would be enough to allow for the plank shrinkage/expansion.

[Mrleft8]

I used PL premium on the keel/centerboard trunk joint on my Cat'spaw dinghy. No issues what so ever as of this posting. 3 years in water for 5 months, 7 months in the rafters of my barn per year.

[Gary Bergman]

We,ve been thru some rather 'heavy seas' in the last four years, working seams to the max at times. 5200 over properly installed cotton works the best for us. I have heard of fools using various types of caulking in tubes without caulking in cotton first, and the stuff doesnt travel very far into the edge joint, so perhaps they do sink...fair enough, says I. Caulking is still done with cotton or oakum. Paying is done with 5200 etc......

[Bob Smalser]

Apples and oranges.

PL Premium is a thick glue that dries hard, 5200 is a rubbery sealant that needs gobs of clamping pressure to perform as a glue at all once immersed.

http://www.woodenboat-ubb.com/vbulletin/upload/showthread.php?t=6799

http://pic3.picturetrail.com/VOL12/1104763/7738131/103956088.jpg

[paladin]

and whats wrong with ferrocement...Liberty ships were built that way.....

[RonW]

A few first hand experience comments. I have used in boat construction all 3 above. 3m5200- p.l. premium construction adhesive- and p.l. window and door caulking.
First off remember that some people do not use the products properly, they try and fill large gaps, and use it as a fillet and so forth, uses that the products are not intended for, and in situations such as gap filling and fillets, you need to use epoxy.

I have used plenty of 3m5200 and I have no intention of using any more of it, I am not a fan of it.Used thinly and clamped or screwed or nailed, you are not going to get 2 pieces of wood apart, used in a big glob, it will pull apart or along with the aid of a hot putty knife.
It deteariates badly when subjected to the sun, it is not paintable, paint will peel later, it oozes a greasy solvent constanly and that I believe shortens it's life span,it also takes 7 days to fully cure, and cost $12, a tube, which takes 12 tubes to make a gallon or $144. a gallon.It is also very nasty to clean up, although the pl premium and door and window caulk aren't very far behind as well.

The p.l window and door caulk, impresses me highly, it doesn't ooze a solvent or feels greasy, and as designed is not going to break down from u.v. rays. It is paintable, and cures very well overnight, it also has a lot more flex and almost but not quite as much adhesive qualities as 3m5200, it also states a 50 year life. In fact a while back, oyster posted pictures of a boat he built, useing barrel staved construction, and vulkem poly caulking in between. Basically the same stuff, just a different brand name.Excellent.

As for gorilla glue, well whoever designed the marketing on this stuff is a genius, But personally I think it is unadulterated krapt that has no use what so ever in boat construction.It just turns to a foam. I have also bought and played with other liquid polys and there are much better, very pricey but again I am not impressed.

P.L.Premium construction adhesive, and that exact name, not one of the subfloor or other types or brands, like henry's or dap or whoever.
This stuff when used properly is as good a wood glue as you can buy, it exceeds resorcinol with softwoods, and not very far behind with hardwoods.And I believe it has a longer life, it claims to last as long as the objects glued together, but I don't believe that 200 years from now 2 rocks you glue together will still be stucked together.
Everything has limits.
Most people use it way too thick, I use a putty knife to spread and thin it down, clamped snugly and or screwed or nailed, after it cures in about a day or so, totally, the wood will not come apart, period.
It is also 100% waterproof.
I talked to the company's tech's, they have no problem in it being used in boat construction.This stuff has slight gap filling capabilities,it is flexible and strong as hell. I have compared breaking open joints with it, as compared to epoxy and the p.l. wins everytime hands
down.

Personally I really think people are missing the boat in not useing this glue in cold molding. It has slight gap filling qualities, I believe a stronger and longer lasting glue line, a much more flexible glue joint, one that is not going to break down from heat or cold.And a glue joint that when stressed to the breaking point will not shatter like epoxy does, but has to be constantly pulled with more and more pressure to get released, and it takes wood with it.It works out to $36. a gallon and is convenient to use, as well as a whole lot less toxic. Being in a caulking tube, it is not made for cabinetry joinery, and should not be used as a fillet, or wood putty.
If you researched, I have said this for over 2 years at least, and still am under the same opinion. Great stuff..It works....

[Bob Smalser]

P.L.Premium construction adhesive, and that exact name, not one of the subfloor or other types or brands, like henry's or dap or whoever.
This stuff when used properly is as good a wood glue as you can buy....

It tacks up so fast it will never be possible to use it in several marine applications that require lots of open time.

Test whether you can use any of these glues for your application before you buy into somebody's recommendation.

[Bob Adams]

I've been surprised, following some of these discussions. I always thought that 5200 below the water line was frowned upon, if not outright dangerous. Did I miss something? I don't have any experience in this regard, except for a local boat which the local yard recaulked with 5200 and subsequently sunk as a result.

I have used 5200 in certain applications, but you should never, ever, use it as a caulk!

[RonW]

Hey Bob, granny was slow, but she was old.

Strange I have never had this problem.

But then again bob is right, do your own experiments.

[willmarsh3]

Here are my own first hand experiences with using 5200.

1) Catalina 25 (Fiberglass) seacock mounts made of pvc and bedded in 5200. These lasted the 4 years I owned her without any sign of deterioration or leakage. I had to enlarge a seacock for a galley sink drain once so I just drilled out the whole pvc fitting with a hole saw to make a bigger hole. The bedding for the fitting was still good.

2) Wittholz steel hulled ketch. I bedded a pvc fitting just below the waterline around 1998. The bedding is still firm.

3) 5200 was used to secure teak to the epoxy coated steel deck of the Wittholz. I am in the process of replacing the deck. The teak was laid about 20 years ago. Parts of it where the glue joint was really thin were still secure to the point that I had to destroy the teak to remove it.

Will.

[Bob Smalser]

Hey Bob, granny was slow, but she was old.

Strange I have never had this problem.

But then again bob is right, do your own experiments.

I wouldn't have tested PL at all if you hadn't turned me onto it.

It's the only GP glue out there that'll stick to Titebond residue, which alone makes it a boon to those who built their strippers with Titebond without realizing that epoxy doesn't stick to it, and that you can't feather in a sound repair to a Titebond stripper using epoxy.

So I'm using PL more and more these days....but that doesn't mean it's stood the test of time as a marine glue....I doubt it'll remain viscous enuf for a 30' layup in warm weather.

[Andrew S/Y Rocquette]

So. I need to re-bed a lead keel. What is the suggested sealant (not adhesive)? I was thinking 5200 is goosd for this application...?

[RonW]

Well thanks Bob...

I think it is a great product. I have used several of these P.L. brand products, and the company is here in ohio, so there is a good distribution on their products.

The main thing I like about these products, any of them, they all seem to do exactly what they say they will do. Which is amazing in todays world.

The first time I used a P.L. product was exactly 32 years ago, and yes it was a subfloor adhesive, and after 2 days the plywood will not come apart from yellow pine floor joists, it rips both apart, unbelievably. And 30 years later these floors still have no squeaks.
The P.L. company seems very straight forward with no bull. As I have stated other places, the 3m co. stutters and does not want to say exactly this or that.
But we have another report from willmarsh who speaks highly of 3m5200, everything seems to depend on the application...

P.S. hey bob, like you I was very dissapointed in the liquid poly's, I thought they where going to be the cat's meow, but guess not...

[sdowney717]

PL also comes in gallon cans.
they had one gallon can at HD and then discontinued it.
I think you might be able to help get around the open time on long pieces by using the pl on both pieces to be joined. that way it could adhere to the wood first on both sides and then when long pices are clamped together, it would mush the glue line and break down the surface cure on the glue.

[marsbar]

Now, this thread is really getting to the meat of things! My original question was directed at how PL Premium or some other "non-5200" product would perform as the bedding material in a plank on frame rebuild....aka Don Dannenberg type bottom.

My take on things is that adhesive properties is less important than flexability in this application. The original material Chris Craft used was an impregnated piece of canvas. The bedding would have to act like a gasket between the inner and outer planking, and still allow for movement of the outer planks from swelling and shrinking. Open time needs to be long enough to work on an area under a single plank at a time. Bottom planking will be held in place by thousands of SB screws into frames and aux-frames etc. I know I may be missing something, but you get the drift.

Thank you all for your valuable replys...and lets keep this great info coming!

[marsbar]

Has this thread been wrung dry already? I can't say I have enough convincing evidence to take the plunge into substituting PL for 5200 in my specific application of the new bottom. Just too much at stake. Hopefully in the future, there will be more on this debate.

Thank you all for your input.

[Ross M]

One further note - there are at least two PL Premiums; PL Premium Polyurethane Construction Adhesive and PL Premium Wood Glue. Both are polyurethanes.

The MSDS data I posted above reflects PL Premium Wood Glue. The MSDS for PL Premium Polyurethane Construction Adhesive shows much lower Isocyanate & Diisocyanate levels.

PL MSDS Sheets (http://www.stickwithpl.com/msds.asp)

[Bob Smalser]

Mike Fonville in North Carolina reports a lamination failure using PL Premium Construction adhesive. You can contact him via the Messing-About.com forum.



http://pic20.picturetrail.com/VOL12/1104763/2595357/151170021.jpg


I have just had a failure in laminating two pieces of fir plywood together with this product. I had used a notched trowel, covering one layer of wood with it and then clamping and weighting it down, and screwing the borders with washers. I cut out the well section of the Simmons and wanted to see how good it held and used a stiff putty knife to part the seam of the two pieces. It crumbled apart. I did notice that the notched glue still had the grooves it it, and the high areas just plain let go. I should have taken a picture of it, but was so pissed and I took apart the complete works and started over. The shot of the transom shows the fir that is also faced with an Okume skin now. THis is how we can buy it. The interior parts of the plywood is not bad at all.

I have a secondary well cutout since I will be doing a second Simmons. Its so efficent to cut two parts, in the process, so I decided to check out the second one. This is what I have this morning. When I get through with my honeydo projects this morning, I will continue on and see what I have in this one. There is something fishy about this layup.

(Clamping pressure problem?)

Well I never did like the bubble finish that it gives when used in simple battern gluing when it expanded out along the joint. As far as big jobs, and lamination, there are many times that the application does not allow for flat weighting down. Even with flatweights, to clamp in the larger laminations such as the transom job off the work site, there is just too much left to question, given what i have now experienced here. ANd in clear finish jobs, screw holes all over the place with clamping washers will not be possible.

I think I will personally forgo recommending it for anything other than a seam compound given all of the mess thats also associated with it. It may work for a one foot square or so on a small boat. But given also the mess down the road, with a complete bond to remove the parts, if the glue does bond well, I think I had rather rely on the thickened epoxy, in the two types of glues, cause I know what epoxy will do.

As a side note, my varnished deck, cypress and mahogany trim strips are laid in the PL window, door and siding sealant and I have no no release with it in over one year now, and its had a full four season weather on it. And I have also used it in laminating keels and the parts can be removed without a complete disaster with a razor knife and a bit of finesse with a chiesel or rigid putty knife like I used to split the two laminates of plywood.

[Gary E]

Mike said this....

I have just had a failure in laminating two pieces of fir plywood together with this product. I had used a notched trowel, covering one layer of wood with it and then clamping and weighting it down, and screwing the borders with washers. I cut out the well section of the Simmons and wanted to see how good it held and used a stiff putty knife to part the seam of the two pieces. It crumbled apart.

Did he expect it to do otherwize? I mean you remove the mechanical fasteners, then pry it apart... and he has gaul enough to call that a failure? ANYTHING and EVERYTHING will fail when pried apart.

[RonW]

O.K. now we are getting into a good thread with hard core substance.
The posts that relate failures are the best and most informative posts. But to get to the root of the problem, you have to analyze why it failed, what was done wrong.
I am glad bob posted the problem.

If you want to say, hey epoxy is the only way to go, then stop and go through many years of posts on this board, and you will find hundreds of problems and failures with epoxy as well.
But there is always a reason.

Oyster is pretty slick, but on this one I have to dissagree.
First off, there are many different notched trowels, and a notched trowel should be selected that will spread whatever to a thickness and spaces inbetween, as to the consistency of the product being spread. So that when something is placed on the ridges left by the notches, and pushed down, as in oyster's case clamped or screwed, that the ridges of the product will push down and basically the ridges will touch each other and create a uniformity in the product.
But we are not talking laying tile, but we are talking laminating wood.
Would you take epoxy and laminate with it in ridges, no you wouldn't, you would spread it evenly to have uniform coverage and complete contact, leaving no AIR GAPS AND VOIDS...

I am sure the guys using 3m5200 are spreading it out, or using a very small notched trowel, as 3m5200 is thinner the P.L. Premium construction adhesive.....
As in all glueing or laminating of wood, leaving air gaps, voids, or too thin of a glue line, as in starved glue line, or in some glues too thick of a glue line, are always going to lead to failure.
Think about what you are doing guys, before you start blaming the products...

Several times I have tested 3m5200, pl premium and epoxy side by side, with the same results, 3m lets go first, epoxy second, and epoxy lets go completely as in a hard glue that cracks open, and last is p.l. and then you have to continue to rip the joint apart, pulling wood with it....But I am sure they is going to be those that love it, and those that say it ain't as good, just use it right before condemming it...uniform even coverage, as with all wood glues...including epoxy..

[Paul Denison]

Nice post Ron. I was all hyped about the PL (did he use construction adhesive or the wood glue?) until I read Mike's post. I usually take Mike's advice like the Gospel, but I believe you may be right on this one. However, what do you think casued the PL to "crumble"? This does not sound like a void problem.

[allananicol]

Hi guys, this is all very interesting, and some of the products you mention are not available is Aus, but what about the use of promoters or primers to aid adhesion, any point in that???

[ddeaton]

Never Mind, I opened my mouth before I read all

[Bob Smalser]

I was all hyped about the PL (did he use construction adhesive or the wood glue?) until I read Mike's post. I usually take Mike's advice like the Gospel, but I believe you may be right on this one. However, what do you think casued the PL to "crumble"? This does not sound like a void problem.

It's been said many times that construction adhesives have relatively short open times, making them a questionable choice for large glueups like a lamination. PL Premium, in particular, also doesn't work at all without good clamping pressure. Add those two factors together in warm weather and you shouldn't be surprised if there are problems.

http://pic20.picturetrail.com/VOL12/1104763/7738131/102357575.jpg

[Dan McCosh]

The role of the sealant between layers of a double-planked hull is not that of a glue. You are looking for minimal adhesion, waterproofing and flexibility. I would be looking at other kinds of sealants as a substitute for 5200--most specifically something that is antifungicidal, flexible, and does not mind lengthy submersion. Liquid neoprene roofing compounds come to mind. Most urethanes aren't particularly happy with long-lasting immersion in water.

[pipefitter]

I had the same issues using the pl poly adhesive as Bob states with it skinning over too quickly.It works great in joints the size the tube was designed to glue. I suspect what Oyster was trying to do with the notched trowel was to scratch it in to the surface and break the skin of the glue and with more uniformity than would be possible in short time with a straight bladed trowel or knife. Notched troweled adhesives also creat a suction on the parts as it displaces the air in the voids even before glue has set.Ideally,it would be a great help if there was a retardant that could be misted over the PL to keep it from skinning. I found that when squeezing it out of the tube,the wood itself also pulls the solvent of the adhesive and the weight of itself,doesn't allow it to give a wet application beyond it's immediate point of contact. It would have to be scratched in. It really seems it would be difficult to use on large or lengthy areas were extreme pressures from fasteners are needed to break the skin.The idea of gluing both sides seems like it would help so that there is no dry contact. That's where epoxy shines. If there is enough in the joint,the whole surface area will have had a wetted contact.Only epoxy joints I have seen fail is where the joints were too dry and absorbed the resin before they were put together. With a sealer coat of resin on plywood that wets it out enough(saturated) so that it doesn't pull excess resin out of the glue line is really hard to imagine being able to ever pull it apart. Anyone that is able to seperate it with a putty knife just isn't getting enough in there or the surface is too dense such as white oak. The pieces joined should slide around a bit before it is at it's final designation. Epoxy needs to also be thick enough to stay in there. If it keeps leaking out of the joints after the fact then it isn't. If you laminate 2 pieces of ½" ply together and it still equals 1" then there isn't enough adhesive.It should be 1/32nd oversize.

[straycat]

My head is spinning reading all this info! Lets cut to the chase here. Without all the technical reasons, what should be used on a 19' double cockpit, double planked hull, under the water line? This boat will be used regularly in summer months for day use and on a trailer when not. Thanks, Lon http://www.woodenboat-ubb.com/vbulletin/upload/showthread.php?t=49788

[RonW]

Here is the way I use P.L. as in a boat, I squirt it on from the tube, and then I take a putty knife and spread it evenly and relatively thinnly, I think too thick and you will see failure. Also agree with bob, it does require or need reasonably good pressure. Nothing like resorcinol does, or any where as near as tight fitting joints.
The notched trowel deal can be tricky, as to depth and width of notches, but would be a good way to get uniformity to start with, but again, I would then use a putty knife to have uniform and even distribution as well as a thin glue line.I think from what I am reading is that too many people are using it way too thick, or not enough clamping pressure. As for oysters failure, I am guessing that the notched trowel was too deep and the notches spaced a little too far apart, My guess.....
Remeber all these different glues and gooks need different thicknesses of gluelines for that product, too thin or too thick can lead to problems with some adhesives.

A couple of thoughts on glues and gooks.-- I watched just lately a glue and adhesive special on the discovery channel. One glue they are using is for heavy galvanized metal in metal building const. They glued instead of riveting these pieces together,(structural members) and the glue was so strong the metal would rip before the glue line failed. Neat I say. BUT....BUT.--
What happens in 40 or 50 years if the glue deteariates, oxidizes or what ever, and then what, one day the building collapses..
Maybe I am geting old, but I just don't have the blind faith others do.

Another thought, what about pickle barrels, or better yet whiskey barrels, they hold water or better stuff. There is no 3m, pl, epoxy in between the joints or is the outside coated in epoxy and cloth.
Of course they do have barrel bands that might be bothersome or look a little funny on your boat.

Maybe we are becoming too dependent on glues and gooks.

Another point is all these gooks have a life span, and I would guess for the most part somewhere between 20 and 50 years. Hot dipped galvanized fasteners should last around 25 years in salt water, and maybe 75 years in fresh water, so what is 30 or 40 years for a gook.

Look at some of these boats for sale on the internet that are 100 years old, wood on wood with bronze or copper fasteners and that is it.....
So if you are building with plywood and gooks, don't expect your great grand children to be having a blast with the boat 80 years form now, that may just be the reality to it all....gooks and glues will fail sooner or later........and can be touchy about there applications..

[Gary Bergman]

I've become lost as to the general thought here. I have only interjected information regarding the paying of seams in carvel planked vessels below the waterline. As far as laminate glues, I have no input. As far as paying substitutes for red lead mixes, this is where I use and can recommend 5200 as a good ten year replacement. Aside from myself, those who are familiar with Richardsons Bay in the SF area should look at and consider Chantal, the most famimiar large schooner in the general anchorage. Mileage from all around the Carribean, as well as the years on the hook in Sausalito. Over 10 years with 5200, no problems. And on the 'age' issue, when 5200 becomes old below the waterline, it comes out relatively easy when the joint is reefed out for new.

[RonW]

I don't think there is a general thought.
there are too many opinions, success stories and recomendations, and failures and problems as well.
Too many variables for a unamimous yea or nay.

[Gary E]

Long ago there used to be kit boats, are there any today?
If there are, the manufacturer would have in the kit, ALL the required
materials, screws, etc, INCLUDING their FAVORITE sealant.

[Grouchy_Old_Coot]

Not to be a Johnny Come Lately, but I have consulted many boat restorers, shipwrights and chemists and no one can agree on what is the best product – but there are a lot of very passionate opinions out there!:eek:

What I have learned is that there are two basic camps – those that swear by polyurethanes (like 3M 5200) and those that use nothing but polysulphides/polysulfides (like Boatlife Life Calk) when it comes to bottom bedding compounds, not as an adhesive.:confused:

I have heard stories of bottom boards being stuck for life once using 3M 5200 and others claiming that after a year of use the 5200 became one large goo-pad that could easily be peeled away. I have been told horror stories about Life Calk being used as a bottom bedding compound and it oozing out between the seams! Somewhere in the middle of all this there must be some truth. :p

Isn’t it all dependent upon the material’s intended use (sealant vs. adhesive), the type of vessel it is used on (trailered vs. slipped) (runabout vs. yacht) and the environment used in (salt water vs. fresh) (plywood vs. plank)?

[Frederick Bolton]

I am responding to this thread just so I can monitor the knowledge. I am just learning and there is a wealth of knowledge here. Keep it coming.