epoxy coating a wooden boat

Hi I am very new to this , I have bought a 26 ft wooden cruiser , I would like to fibreglass it , I purchased some r180 epoxy resin and hardner as well as dynel cloth and matting .

I have been advised to paint a thin mix of epoxy coating 1st ( CPES )

Do I do that and then epoxy resin over the top and then matting etc .

How many coats of thin epoxy and how many coats of rein and matting will I do

This is probably too much info ask for step by step instructions , but a good start would be great cheers michael

 

West Systems has some good information to help you.
http://www.westsystem.com/ss/use-guides/
It would be a good place to start.
Gary

 

Much depends on the type of wooden boat you have. Many types of wooden boat construction don't lend themselves well to epoxy. CPES (brand) or other penetrating epoxy is a waste of time, money and effort, but go for it if you have plenty to spare.

As a general rule, traditional wooden boat construction methods don't take well to epoxy. On the other hand, some do, particularly plywood construction.

The basic problem is, once a boat is built, you can't fully "encapsulate" the separate pieces, which is what makes epoxy so effective at preventing rot, sealing wood, etc. If you can't encapsulate the part, the epoxy is nothing more then really expensive paint and not a good idea, as it'll trap moisture in the wood, with limited avenues for it to escape, increasing the potential for rot.

In short, what do you have, it's construction method (pictures are very helpful), etc.?

Yes, there was a time when CPES cured everything and epoxy was the answer to all boat issues. Now, restorers and builders are finding out that this isn't the case and like every thing else in live, there's a time an a place for epoxy and also times when you just shouldn't use it.

The "blanket" approach with epoxy is still strongly adhered to by many, but those of us that actually do this sort of thing daily know better.

You may also find this site interesting (http://www.woodworkforums.ubeaut.com.au/forumdisplay.php?f=29), where I also participate, but supplies, brands and locally available "stuff" is obtainable.

 

Hi thank you for that , it is a plywood material, I was going to put a complete skin of fibreglass matting from deck to keel etc I have stripped the paint completely off and wanted to add protection from salt water ets on the outside , cheers michael

 

"I have been advised to paint a thin mix of epoxy coating 1st ( CPES )

Do I do that and then epoxy resin over the top and then matting etc .

How many coats of thin epoxy and how many coats of rein and matting will I do"

OK, the thinned epoxy coat (s) is to penetrate the plywood as much as is possible for this to occur. 50% thinned for the first coat, 25% second coat, then finish with a straight coat.
This is going to give the plywood the best protective coating that you can give it (using the epoxy method).

Sand down when completly cured and then start on the laminates. Before starting lamination, precut all the cloth and drape it over the boat in sections so that you know all is OK, when ready to wet out, you again paint the boat woth resin (rollers) then drape the cloth over the section you have just wet down, and continue along using this process. Only wet out as much as you intend to finish in that cycle.

Epoxy when mixed has of course a pot life, so get the epoxy out of the mix pot as soon as possible, evenly spread out on the boat it will take much longer than sitting in the pot, so tha will save a lot of waste if you did not know that.

Have fun, I did an epoxy/dynel boat in 1972 and she is still like new.

 

CPES is a waste of time as I mentioned. Use straight epoxy instead. Don't use mat. It's designed for resins other then epoxy. Epoxy doesn't need the support of mat. Use cloth instead, 8 ounce is a typical light weight sheathing.

Do not thin the epoxy! It's not paint, nor varnish, no thinning unless you really have an understanding of the chemicals involved. Judging by the nature of your questions, you don't. I've met very few people who understood what they were doing when thinning epoxy. Thinning it actually weakens epoxy a lot, which is exactly what you don't want. By the way, CPES is pre-thinned epoxy, which is why it's not any good for what their advertising claims it is. Straight marine grade laminating epoxy is 30%+ more solids then CPES and other penetrating epoxies and considerably better at resisting moisture vapor penetration in wood, which is why we use it to seal wood in the first place. Put in a nut shell, straight epoxy will easily out perform straight CPES (or other penetrating epoxies) in identical, side by side moisture penetration testing. This isn't speculation, it's proven fact, easily understood by those among us with a chemical back ground (like me).

Log onto the major formulators web sites and look at their "user guides" look up what they say about thinning epoxy. Also have a look at techniques, methods, reinforcement additives (fillers), fabrics and applications. These guides can answer a lot of your questions.

Another tip, who ever is telling you about CPES and mat for use with your boat is about two decades behind the current testing and long term durability studies that have been conducted. I suspect they are equally off base on much of the advise they're offering, so stop paying attention to them, just nod as if you believe them and move into the 21st century wiser and without insulting offers of their dated help.

 

PAR,

Epiglass in NZ have been recommending this technique for years, they have had exceptional results doing it....they have been making epoxies and using them longer than any of us......

 

They market Everdure, now by International Paints, it is a fungicidal epoxy, thinned down it certainly does penetrate plywoods, I have cut and tested and used this product for as long as I can remember, I am sure it has saved hundreds of ply boats from the wreckers.

 

You can put a lot of things in epoxy, as a formulator, but the user is strongly urged not to do so. In most cases you just cut down the molecular cross link, which weakens the epoxy dramatically. An unfortunate side effect is the lose of solids content due to out gassing of the solvent(s). This makes for a permeable membrane, not a 100% solids seal coat.

A quick look at their product sheet shows only 21% solids, compared to regular laminating resin which is 100% solids.

Repeated tests have clearly proven, it's not the depth of penetration that makes a good moisture proof product, but the quality of the coating. All these "penetrating" products make their selling points on the ability to soak in. So what, it's the quality of the product's ability to resist passage of moisture vapor, that is the trick to water proofness, not penetration depth. I don't care if it soaks all the way through, at 21% solids, it's a soup strainer compared to laminating resins, in regard to moisture vapor.

In fact all the major "penetrating" epoxy products recommend over coating with some sort of higher solids content material (read regular epoxy). Hell even there own Interprime 820 primer (epoxy) has 47% solids and it's just a paint.

This penetrating epoxy thing was a marketing tool a few decades ago, but it doesn't work in real world applications, without the assistance of high solids top coats, which naturally forces the question, why bother with the penetration coats in the first place.

The only time a penetration product is helpful is when you have slight surface damage. A penetrating epoxy can get below this, firm up the soft wood and provide a good bond coat for additional applications of top coat products. If you have more then slight surface damage, then you have to cut back to good wood or replace the piece, because no product can turn rot back into a wood like material. This is what some of these penetrating epoxies try to do.

If you flood coat a shallow pan with it, let it cure, then pull the thick film out of the pan, you'll find it's not hard, but rubbery (depending on modifiers, formulation, etc.). The idea is to reassemble (saturate and bind) the rotted wood fibers into a sort of wood like material. If it's a static piece, then this works well.

Architectural details on homes is a common place you see these products work exceptional well. A rare, hard to reproduce piece of crown molding (for example) full of rot and decay can be rejuvenated to a fair degree, though it can't take any loading, flexing or other stress, but it can look pretty hanging on a wall.

My point is, there are applications for these products, but they're not the cure all they once (and still by some) were touted to be.

If you need penetration, for whatever reason, a much better method is controlling viscosity with temperature. This way you get 100% solids resin, deep into the fibers and no need for over coating (except UV protection of course) is necessary.

Naturally, companies aren't going to stop offering something that still has a following and they're certainly not going to publish testing results that contradict their advertising claims, but they all know the truth, both chemically and physically is respect to the properties of their penetrating offerings.

A simple test can prove all the bull surrounding this. Take two pieces of hardwood, drill a large, flat bottomed hole partly through each. Of course each should be the same size, weight and hole depth. Coat the inside of the hole and top with your product of choice and the other with a good quality laminating resin. Now, fill both holes with water and see which one picks up weight across a time frame. I can guarantee the penetrating epoxy (alone of course) will permit moisture to pass through, making the wood measurably heavier. This is a clear indication of it's abilities as a moisture barrier.

One of the coolest tests I've seen was a balloon of epoxy and a CPES like product. They were molded over a Mylar balloon, then the balloon burst, removed, a tablespoon of water added then the thing sealed with a "pressure bandage". A week later there wasn't any water left in the one, but the regular epoxy balloon still had it's tablespoon full inside.

 

"there are applications for these products, but they're not the cure all they once (and still by some) were touted to be."

Yes, true, if you read PAR the initial post, Micheal fully intends to cover the "watered down " layers with normal laminations.

As you know, I do not ever see anything you write being "wrong", just different opinions, but you certainly feel that the penetration bit is to no avail, and I respect your opinion of course, however I am writing from many years using this system, and certainly have had very good results doing so, I fail to see why you do not think that deep penetration by the epoxy is not a good thing, surely if the wood has a thorough soaking the effect should be beneficial. I am more than happy to change if there is good reason to do so, maybe you just feel the watered down is a waste, but i see it as forming a rigid base for a good topcoat, sort of like painting alloy, no good applying a fancy linear poly over raw alloy.....it is the substrate that holds it all together in the long run.

 

Applying a less then waterproof, rubbery coating, regardless of it's penetration ability, is a step best skipped.

It doesn't dry hard like regular epoxy, it cures rubbery and permeable. Besides, you can get the same penetration using regular epoxy with temperature, which does cure hard, puts 100% solids material just as deep as the thinned stuff, plus it's waterproof.

Again, penetration has nothing to do with waterproofness. The ability of the coating to resist moisture vapor is the only consideration in this regard. If you want penetration for some reason (I can think of several) then viscosity is easily controlled without resorting to ruining molecular bonds within the cured epoxy molecule (added solvents).

Now it is a good primer, but frankly there are better primers, which offer more moisture resistance. There are applications for this stuff, but I know people that literally coat everything with it. I use to be one of these people, but then I saw some testing results, conducted my own tests and found more testing results from other sources. It didn't take me long to realize all the barrels of this stuff I've used, weren't necessary, if I'd used different techniques. I now employ those methods, save a bunch of time money and effort, with the same results and durability, which is why I consider it a waste in most building applications.

The best bond you can get with wood, is a "hot on hot" (okay hot on hot, but cooling) regular epoxy application, preferably one that gets post cured too. No diluted goo, no solvents, just 100% solids, cured, fully cross linked molecules (actually just one big molecule) of thermoset plastic as the binder and moisture barrier.

 

Thanks PAR for that explanation, I certainly will look into it.

 

A deep penetration is desirable of course, it adds a lot of strength to any sort of wood. Years ago I used a dilution from R&G, that did not weaken the crosslink, too. That was just a waste of time and money. Later then Apex (Richard) showed me how they do in Turkey, using a very low viscosity resin and a slow hardener at high temperature. It needs to be postcured at about 120°C but gives a very strong material.
Sasha

 

PAR, your lectures are very good.

I was under the opinion that CPES would penetrate deeper than F/glass resin.
I put the CPES on the Deck to deepen the grip and the Fiberglass paint on top of the CPES coated deck.

So now if the Sun can penetrate deep enough to go past the Paint, and the CPES, the Lignons etc will still be destroyed by the Ultra-violet rays and eventually the CPES will come loose, and the Fiberglass paint is still stuck solidly to the CPES, it will come up too.

So how do we get the Fiberglass paint to penetrate deep enough to beat Ol' SOL and his Ultra-violet rays?

 

I'm not sure I understand your question Thudpucker. penetrating epoxy on wood isn't as effective as low viscosity epoxy (either formulated or with temperature control).

Penetration isn't as important is it appears or would naturally seem. When tested, the bond breaks through the wood fibers, suggesting the polymer exceeds the elongation strength of these wood fibers. It would seem the deeper the penetration the better the grip, but in reality the stress is transmitted through the polymer to the fibers, regardless of the depth (at least in the typical penetration depths possible with penetrating epoxy or low viscosity epoxy) where the modulus of the fibers is strained to failure. Coupled with the water proofing ability (or lack of it with most penetrating epoxies) of epoxy, it becomes just a simple business decision to discontinue penetrating epoxy use, in favor of low viscosity resins (like Raka or other specially formulated low V goo).

As far as UV penetration to a substrate, there's only one prevention that I know that's effective, top coating with a UV inhibiting material. For most applications this means paint or a clear coat of some sort. I've done some research on clear coats in regard to long term UV exposure, but my tests fall in line with what Paint manufactures and epoxy formulators already know. In short, if your UV protection is degraded, it doesn't matter what kind of goo you've employed, it will also degrade with damage to the substrate very likely as well.

I wasn't trying to "lecture" . . .