View Full Version : C.P.E.S. under epoxy, paint & varnish

06-17-2002, 09:30 AM
I am about to have a boat professionally built. I have concluded that Smith & Co.'s Clear Penetrating Epoxy Sealer should be applied to all wood surfaces before being coated with either epoxy resin, paint or varnish. In other words, a tie coat between the bare wood and any top coat.

My question, for those experienced with C.P.E.S., is how many coats are required? Two? Three?

Thanks for the help!


Scott Rosen
06-17-2002, 09:43 AM

On a project like this, you should be talking directly with Steve Smith at Smith & Co. and the builder. Having said that, one or two coats will usually do the trick for sealing sound, new wood.

Don Maurer
06-17-2002, 10:50 AM
It kind of depends on the wood. I applied CPES then epoxy to my rudder and tiller this weekend. The rudder is hondouras mahogany. The tiller is douglas fir. I found that the mahogany required at least one more coat than the douglas fir. The mahogany is also much more susceptable to bubbles due to outgassing. Definitely apply the CPES in the evening to mahogany, or you will end up needing to sand the bubbles before epoxying or painting. I applied enough CPES so that the surface had a sheen to it after the CPES set. One coat was usually enough on douglas fir. The mahogany took at least two. End grain required considerably more.

Norm Harris
06-17-2002, 06:30 PM
I've used it on my rudder (oak), my dog house (teak), and to attempt to repair a soft spot under the companionway slider (mahogany). In each case I applied it to saturation without letting it dry between coats. It seems that the teak took less than the oak or mahogany.

Since you're coating new wood and don't have to worry about the CPES running onto other finishes, I would just keep laying it on until the wood refuses to take any more.

06-18-2002, 07:25 PM
Thanks, everyone!

Scott, I took your advice and finally called Smith & Co. The Internet is a wonderful search tool and idea exchange. But nothing beats a good old fashioned phone call. Emile answered all of my questions and then answered a lot of questions I hadn't thought to ask. As it turns out, there is a distributor right here in N'awlins!

So, CPES under epoxy, paint or varnish it is!


06-19-2002, 10:07 AM
CPES under epoxy? Why?


Don Maurer
06-20-2002, 09:46 AM
CPES under epoxy? Why? So you have an epoxy bond down into the wood fibers instead of just on the surface.

06-20-2002, 02:13 PM
Yes, one would suppose that would be the reason and desireable if epoxy does not stick to wood very well or if it sticks better to a CPES sealed surface than it does to raw wood. Does it? And, if so wouldn't it be purdent to CPES surfaces to be bonded togeather? On the other hand if a normal epoxy glued joint is in fact stronger than the wood it joins why bother?

Also, if CPES forms a chemical bond between the wood and the finish as is claimed what does one gain by putting epoxy between the CPES and the finish except to substitute a mechanical bond with the finish?


06-20-2002, 03:32 PM

Somewhere in the ongoing discussion about C.P.E.S. between bare wood and subsequent coatings, I recall reading the following suggestion for a finish scheme:
Hull exterior: C.P.E.S./epoxy/paint
Hull interior: C.P.E.S./paint or CPES/varnish on brightwork.
The explanation was that the exta epoxy on the exterior would slow water migration into the hull. The interior side of the hull would have a more permeable coating system allowing water vapor to exit.
That was the scientific explanation, paraphrased.

While I have your attention, are you still in favor of using black walnut and black cherry in boats? I am seriously considering having the Caledonia Yawl backbone built out of black walnut. Cherry rails and thwarts.

Ken Hall
06-20-2002, 03:35 PM
I'm thinking I might CPES the hull of the International Fireball (#3226) I'm about to acquire after I wood it and before I paint it (even though, as a dry-sailed boat, I'll probably only use a good porch enamel).

If the polyurethane-varnished topsides are as good as they looked on first inspection, I might just scuff, spot repair where needed, and put on a few more coats. The paint is in much worse apparent shape than the varnish, but she's been stored indoors since her last use circa 1986.

The Fireball is a low-volume scow, practically a board boat, 16'2" by about 4' and change. Construction is mahogany ply, resorcinol, and ring nails. I know from reading the thread that mahogany tends to take up more CPES than some other woods, but wouldn't the glues in the plywood limit uptake to the outermost veneer? Assuming you're familiar with the hull form, d'you think 2 quarts might do the trick, or ought I budget for more?

BTW, this is my first boat. A retired gent of my acquaintance is giving her to me (he built her in 1968-69). I plan to beat the crap out of her regularly in the process of learning to sail on my own, and then give her plenty of TLC between beatings. smile.gif

[ 06-20-2002, 04:36 PM: Message edited by: Ken Hall ]

Don Maurer
06-20-2002, 04:01 PM
Not having an electron microscope handy, I can only assume that epoxy will chemically bond to CPES. And since CPES does penetrate better than regular epoxy, I assume that the bond will be stronger and tougher than just a surface bond of epoxy to wood. It would follow that CPES under an epoxy glue joint would also be stronger, but since epoxy is generally stronger than the wood anyway, it may not be worth the trouble, unless you are gluing the end grain. I used CPES while gluing on some parts, but it was more to stabilize the wood than for strength.

It is true that you lose the advantage of a mechanical bond to your paint if you epoxy coat (with or without CPES) but it does seem to be a tougher coating than paint so it may be worth it in some cases. It also has some filling capability, so you can get by without a hi build primer.

06-20-2002, 04:06 PM

Paraphrasing again, CPES will only penetrate plywood as far as the first glueline.

I heartily suggest you call Smith & Co. directly. They will answer all your questions and tell you where the nearest distributor is. I know that Zimmerman Boatworks in Columbus distributes Smith's products. There is probably one closer to Cleveland.

Smith & Co. numbers:



06-20-2002, 05:42 PM
Venchka, my opinion is walnut is too valuable and beautiful a wood to use for construction purposes. It is somewhat rot resistant and takes glue well but there are cheaper timber that is as good for your keel. Cherry thwarts and rails will be awesome. Otherwise I defer to others with experience using these woods in boats.

Call Smith and get the straight scoop? Your trying to get yourself thrown out of the old philosophers club, grasshopper. Watch it.


[ 06-20-2002, 06:43 PM: Message edited by: NormMessinger ]

06-20-2002, 06:25 PM
This question about things going past the first glue line in plywood came up a while back, and I recall going into my shop and digging under the sawdust for plywood scraps. I recall finding some T-111 siding, and some maybe seven-ply half-inch spruce, and conventional fir.....maybe something else. I recall sanding a cut edge of each and examining them under the microscope and reporting the observation that glue-line thicknesses varied from about five mils to zero, and there were clearly visible areas where there was NO intact film of glue. What it means is that when plywood is made, a harder winter growth ring may line up with a softer summer growth ring, or even a stretched-too-much area of summer growth, and one layer bite into another, or two summer areas coincide and there be little clamping pressure to those areas being slightly shrunken, or for whatever other reasons, there may not be an intact glue line in plywood, generally speaking, and anything which has low surface tension on wood and wets wood fibers could easily flow past a glue line.

paul oman
06-20-2002, 08:43 PM
Why not make your own and save a lot of money? Just add a quality solvent(s) to a thin non blushing epoxy. CEPS has lots of solvents in it. You can do that yourself. No magic there.... See tests of 'do it yourself' penetrating epoxy at www.epoxyproducts.com/woodseal.html (http://www.epoxyproducts.com/woodseal.html)


Wayne Jeffers
06-20-2002, 08:53 PM
MAS epoxy with the non-blushing slow hardener is so thin and so slow-setting that I can't imagine it would take much (if any) thinning to get penetration equal to CPES.


06-21-2002, 08:00 AM
To a weldor, penetration is everything. But I'm not so sure that is the case with googue, necessarily. WEST did a test with their goop wherein they tested various dilutions. Undiluted was better. This was reported in their free publication, Epoworks.


Tom Dugan
06-21-2002, 09:18 AM
Sure, CPES may penetrate deeper than a thin epoxy like MAS, but how much penetration is enough, really? Given a good epoxy job, I can't imagine a scenario where the epoxy-to-wood glueline fails without total destruction of the wood.

IMO, CPES under epoxy is a belt-and-braces approach, where the belt is reeealy expensive.


Wayne Jeffers
06-21-2002, 10:08 AM
Has any one done any tests/experiments to see exactly how deeply CPES penetrates?

My own educated guess is, not much. I suspect that CPES's primary benefit is in ensuring adhesion between the wood and other coatings applied to the wood and perhaps retarding moisture gain/loss. For these purposes, I'm skeptical that CPES would do better than, say, thinned epoxy or even coating the bare wood with good paint if it is clean and not oily.

I've found it curious that some of the biggest proponents of CPES and its purported penetration of clean new wood speak very disparagingly of the penetration achieved by applying CCA salts to wood under pressure. How can you argue that CPES achieves such wonderful deep penetration of wood before kicking when applied by brushing/flooding at STP, yet CCA salts applied under pressure to the point where the lumber takes weeks to dry out does not achieve penetration?

I admit that I have not yet used CPES, so I do not speak from experience. I do know that it is very expensive. Some of the claims made for it sound like they come from a snake-oil salesman. I find it curious that almost none of the web sites which offer CPES will publish the price and I have yet to find any information as to rate of coverage. When I see an ad for anything that says "call for price," I usually keep my hand on my wallet and walk away.

Call me septical. smile.gif


Art Read
06-21-2002, 11:35 AM
Wayne, my biggest reservation about P/T lumber for boatbuilding is that every stick of wood in a boat gets re-milled by the builder before it goes on the boat. I don't know for sure if that leaves any "preservative" behind or not, but it doesn't "look" like it. With a CPES treatment, it puts the preservative on the finished timber so at you know that at least the fresh surfaces have SOMETHING on 'em.

Scott Rosen
06-21-2002, 12:42 PM
Wayne, there are published tests about the penetration of CPES into wood. Check the Smith & Co. website for the report.

Paul's tests are useless as far as I can tell, unless you are buying epoxy for the purpose of sealing cellulose sponges and gluing water molecules together. A cellulose sponge does not replicate the properties of a piece of sound or rotten wood. In fact, it's exactly the opposite. In sound wood, there nowhere near the porosity of a sponge. In rotten wood, the cellulose in the wood has been destroyed to some extent by the rot. No epoxy manufacturer claims that it will be effective if applied to a surface that's 100% saturated with water.

If someone wants to compare CPES with other thinned epoxies, then the way to do is to follow the methodology used by Smith & Co.--on real wood--and then report the results.

Wayne Jeffers
06-21-2002, 02:52 PM

Cellulose sponges? Gluing water? What am I missing?

Paul's test #3 appears to have some relevance, perhaps:

Small wooden blocks coated, allowed to cure for 24 plus hours, then soaked in water for several days.
uncoat block = 19 grams went to 28 grams = 47% increase
block coated with Low V epoxy = 22 grams went to 27 grams = 23% increase
block coated with Aluthene urethane primer = 21 grams went to 22 grams = 5% increase
block coated with "CPES" = 21 grams went to 27 grams = 28.5% increase"

Paul compares wood coated with CPES to wood coated with other products for water absorption purposes. I don't think Smith claims that CPES will entirely prevent water absorption, only retard it. Low V epoxy appears to be more effective in retarding water absorption.

Found on Smith's "Wood Restoration" web site: "The Smith & Co. product will penetrate undamaged wood a significant distance (approximately 1/4" through end grain, 1/32" through side grain.)"

1/32 inch doesn't seem like much penetration to me. I wonder how that compares to low viscosity epoxy? Or thinned epoxy? Or ordinary paint? Are there any independent tests?

I just can't bring myself to spend 50 bucks for a couple of quarts of CPES to experiment when the benefits appear to be in dispute.


06-21-2002, 05:16 PM
How can an epoxy that is 70% thinners protect a piece of wood more than a layer of 100% epoxy? Back in the old days Cleek used to rave about how CPES allowed the wood to breath, how it let water vapor pass out of the wood, etc. If it will let it out it will also let it in, no? Best I can tell from all the discussion on this forum, Smith's literature, and my own use of a few pints of the stuff is that it is a sealer and nothing more, which, it is claimed, forms a chemical bond with the finish coat.


06-21-2002, 06:27 PM
There are pictures of penetration on the web site www.woodrestoration.com. (http://www.woodrestoration.com.) It seems to be quite a bit more than a quarter-inch, and to depend directly on where and how deeply fungi ate into the wood.

I don't know of any one else who has done comparable studies.

There are also flexural modulus [how easily the wood bends] tests, which show that the wood specimens with and without impregnation have almost exactly the same flexural modulus.

Since the shear strength of wood is only 200-300 pounds per square inch , it is important that original construction as well as later modifications or repairs not cause local stresses that exceed that. An excessively stiff epoxy can cause local stresses and cleave from the wood where a more flexible product, such as two-part polysulfide or one-part urethane sealants, stretches more and distributes a displacement over greater area, avoiding local failures.

I don't know of any hard-and-fast rule in here....try things and see what works in your case. proper engineering tests can always be done, uisng simple shop facilities.

Depending on the particular epoxy manufacturer, their resin system may change the flexibility of the wood; either none, a little, a lot or too much. The user can decide how much of a change in wood mechanical properties best suits their application, and what tolerable limits they may have.

Any of these manufacturers, including Mr. Oman, could do exactly the same tests that Wedell, Smith and Fraatz did in their paper at woodrestoration, and show how some formulation of their product, thinned or not, affected the mechanical properties of wood.

Sponges, indeed!

Scott Rosen
06-21-2002, 08:37 PM
Wayne, this is taken directly from that site:

Before forming an opinion one way or another about penetrating epoxies, perform your own tests. Purchase or blend up your favorite penetrating epoxy. Put a few ounces of it in a dish or pan and observe it for several days. Pour an ounce or two on a kitchen sponge. . . . . Pour the product into a cup of water. After you've done these tests, then form your own opinion. . . . I also used ordinary cellulose kitchen sponges to simulate ‘bad wood' and applied 1 ounce of my test mixtures to each sponge. . . . I also poured small amounts of both third party, and my own test mixtures, into cups of water to observe their reaction to 100% damp surfaces."

Wayne, I don't care if you use CPES. There's absolutely nothing controversial about it, except that some people say it costs too much.

And one more thing. My daughter says hi. My little girl, Avi. (She's reading over my shoulder :D )

Wayne Jeffers
06-21-2002, 09:19 PM

Okay. Now I see the link I didn't see and follow earlier. The one with the text you quoted.

It wasn't my intent to get into an argument about CPES. As I said in my first post, I'm skeptical. Trying to stimulate further discussion, I suppose. I've read all the discussion of CPES (pro and con) here for the last few years. Other than assisting with bonding subsequent coatings on problem woods, I'm simply not persuaded of its benefits. And I fail to understand what distinguishes it from other thin epoxy formulations that are much less expensive.

Perhaps I'm ambivalent about it, too. The wood on the 47-year-old western red cedar daysailer I'm restoring is in wonderful shape, no noticeable rot, and will probably outlast me, even without benefit of exotic sealers. If I thought I could appreciably extend its life for $50, that's a negligible expense.

There's clearly something about the way CPES is marketed that rubs me the wrong way, as I noted earlier.

I read about epoxy encapsulation before I built my first boat and went to a lot of trouble and expense to give it that treatment. I now doubt it was worth the time, trouble, and expense.

Tell Avi I said "Hi!"


06-22-2002, 04:19 PM
Wayne, you comment about epoxy encapsulation, and there is something about the way THAT is marketed that rubs me the wrong way.

There are two different things being done, and the marketing of them by manufacturers and distributors seems occasionally to be both given and taken at cross-purposes. The marketing and promotional materials about CPES seem to get swept up into that. I see nowhere in that product's literature that it is promoted to stop water from getting in, as are high-water-resistance barrier coatings such as paints or resins. It IS promoted as allowing water vapor to pass, which it evidently does much better than other products, based on the tests of Smith's competitors. Interestingly enough, his competition proves his claim and tries to promote it as a disadvantage, when they are selling something that does the opposite of what his product does.

Many commercially marketed products or home-brew variations are promoted as encapsulating coatings for wood. There is also promotion of those products for the purpose of moisture-diffusion-barriers, as well as impregnating restoratives.

The Gougeons, among others, have done tests that show a fully immersed piece of wood coated or impregnated with whatever, will gain weight at some rate.

Eventually, everything saturates with water. For some specimens, it just takes longer. That is not, however, always the real world. A moisture barrier may be a relative thing, and paints or epoxy coatings need only reduce the rate of water diffusion into a piece of wood to a level where it is exceeded by the rate of water evaporation off the other side. At that point a PARTLY immersed wood specimen stays dry.

I personally repeated the Gougeon's test with their epoxy on a piece of fully immersed wood. It showed incredibly little weight gain for two months, and then a rather abrupt weight gain to about forty percent water by weight, in only a week or so. When wood absorbs water it swells, more tangentially to the growth rings than radially, but 2-3% in one direction and 3-5% in the other. When the 4% or so elasticity of their epoxy was exceeded, it cracked and water came in.

A coating on the outside of a piece of wood reduces the rate of water take-up. A much lesser coating on the inside surface allows that water which makes in through the outer coating to easily escape. It also allows water absorbed by the inner surface to [relatively] easily evaporate back out. This is where epoxy encapsulation [or, in some cases , paints] make sense to me......on only one side, or MUCH more on one side and MUCH less on the other.

All epoxy coatings and painted barier coatings are subject to randomity of life, the physical universe, and may fail. When they do, water leaks in.

The volume of 18 grams of liquid water is 18 milliliters. The volume of 18 grams of water vapor is 22,400 milliliters. Thus, a little water can leak in a crack in epoxy encapsulated wood, but it does not readily get out.

Rot follows.

Wayne Jeffers
06-24-2002, 10:50 PM

Your post summarizes well my concerns about epoxy encapsulation. In a moment of weakness several years ago, I bought the marketing assertion that I could encapsulate wood with a non-permeable (!) coating of epoxy and protect it from the ravages of water.

My experiences over the years, in many different contexts, tells me that water is very, very difficult to reliably keep out of places you don't want it. On the other hand, water is quite easily trapped in places you don't want it, often by the very means adopted for the purpose of keeping it out. As a general rule, I've come to accept that things will occasionally get wet and that often the best means of keeping away rot, mildew, etc., is to make sure things can dry quickly and easily when they inevitably get wet. In hindsight, this is what makes me think that encapsulating my boat when I built it was not worth my time and trouble, and may in the end do more harm than good.

As for CPES, the idea of it forming a bond between problem surfaces and paint/varnish to promote adhesion makes sense to me. However, I fail to understand why any non-blushing low viscosity epoxy would not work equally well and more inexpensively for this purpose.

As I understand it, all epoxy is water permeable to a slight degree. That epoxy marketed as CPES appears to be permeable to a somewhat greater degree, to allow the wood to breathe. I'm not sure of the difference in degree of permeability, but from the results of the limited tests of wooden blocks that Paul Oman posted on his web site, it appears the difference in permeability is not great compared to his "Low Viscosity" epoxy. It would be interesting to know the relative permeability of the various epoxy formulations on the market.

One thing that you said in your last post that makes a great deal of sense to me:

"A coating on the outside of a piece of wood reduces the rate of water take-up. A much lesser coating on the inside surface allows that water which makes in through the outer coating to easily escape. It also allows water absorbed by the inner surface to [relatively] easily evaporate back out. This is where epoxy encapsulation [or, in some cases , paints] make sense to me......on only one side, or MUCH more on one side and MUCH less on the other."

This is consistent with my own thinking on the matter. If one chooses to go the epoxy route, a very low-permeable coating (not CPES) on the outside to inhibit water intrusion makes sense. Say, several coats of epoxy resin, perhaps with cloth depending upon the construction type, on the outside. But, since water will inevitably intrude, the inside should have 1) adequate ventilation and 2) a permeable coating to allow water vapor to pass out of the wood. I'm not sure how an undercoat of CPES would effect the permeability of the paint or varnish topcoat.

Generally speaking, I tend more and more to come around to the philosophy of Tom Hill of "Ultralight Boatbuilding" fame, who said he does not glue with paint, and he does not paint with glue (epoxy). Since my boats are all dry-sailed, letting the wood breath strikes me as far more important than trying to seal out water penetrating planks during a day's sail. It seems to me that paint or varnish finish coats should let the wood breathe well enough without the expense of adding CPES as an undercoat.


06-25-2002, 08:56 AM
Chemist & Wayne,

Precisely! And I think this is the second time that the chemist has put forth the idea of a "more outside and less inside" coating system.

By the way, did I say the boat in question would live on a trailer, in a building in South Louisiana when not in the water? Perhaps I am making too much out of nothing. But, mold and mildew are a fact of life here in the Swamp. AND, ultimately, time and skill permitting, I imagine the boat being in the water for a summer.

Now, how would you treat plywood planking, plywood centercase sides, etc.? chemist, how permeable are the gluelines (assuming they exist-you got me on that first glueline bit) in marine plywood? Assuming 4 gluelines in 5 ply 9mm planking, one might expect that the only way for water vapor to escape is from the surface, whether it be the exterior or interior surface. As opposed to passing from the outside, through the plywood, to the inside surface where it would evaporate?


I respect your opinions and figure you have forgotten more about boat building than I will ever know. While OLD, I am no philospher. The quotes I have so far for my boat include the following for structural wood: Ash, Douglas-fir, Osage Orange, White Oak and maybe Black Locust. Temper that with the fact that the builder whose work I can afford has access to douglas-fir, white oak (fresh from the sawmill), ash and walnut. Given those choices, my limited experience and research points to walnut as having the best combination of qualities-availablity, rot resistance, ease of working, gluing and cost.

Am I making any sense?

in the Swamp

Wayne Jeffers
06-25-2002, 10:12 AM
Wayne in the Swamp,

One thing regarding plywood building upon which there is near universal agreement: You should seal the edges of the plywood well, as it is very prone to wick up water through exposed end grain. Epoxy works well to plug those little capillaries in the edges.

As to structural wood, walnut is okay from a strength standpoint, but its rot resistance is only fair. Of the woods you've mentioned, my choices, in order, would be black locust, white oak, and Douglas fir. I would pass on the Osage Orange except for parts that I could saw, because it's such a bear to work, and I would pass on ash, because the ash in this area is low in rot resistance (not sure about ash growing in Louisiana.) If you have walnut, you could probably swap it for a greater quantity of white oak.

in the Ohio hills

06-25-2002, 10:44 AM

From the USFS Forest Products Lab, regarding walnut:

"Durability: Rated as very resistant to heartwood decay—one of the most durable woods, even under
conditions favorable to decay."

Is this true or false? Or are there other forms of decay that will kill walnut?

The builder I am leaning towards is in Northwest Ohio. There are two sawmills within an hour of his shop. One has kiln dried white oak. The other has white oak logs which can be cut to order. Do you have any experience gluing Ohio white oak? There seems to be a 50-50 split on white oak glued with epoxy. Half say it works, half say it doesn't work. I guess I could ask for resourcinal glue. Or back up the glue with bronze nails and screws.

As for the Osage Orange, that builder is in Texas. He has a stash of osage and will cut/mill/laminate any part of the boat out of Osage Orange. Darned heavy to use too much of it. And he's darned EXPENSIVE! But, I would end up with a very durable framework for the boat.

What do you know about sassafras for non-critical areas? It's available from Homestead Hardwoods in northern Ohio. I was thinking of using it for the floorboards.

Thanks for your help!

soon to be a boat owner, maybe

Wayne Jeffers
06-25-2002, 11:29 AM

Many of my comments about durability of odd species of wood come from my own observations of wood over the years in the neighborhood of my house.

I cut and sawed a large walnut tree near my garden some years ago. It didn't take but a few years for the stump to lose its grip at the top of the bank and go sliding over. Its large roots rotted in two. I think these are generally a reliable indicator of qualities of heartwood. I cut quite a few ash trees (not sure if they were white ash or green ash) from the property and it didn't take long for those stumps to rot away.

I have some stumps of black cherry and sassafras that I cut some 20 years ago. They're still quite solid.

Commercially, I think the walnut is much more valuable and could be traded for a much greater quantity of whatever species of wood would best suit your design.

I have no experience gluing white oak, but I've heard mixed reviews. Try the search feature and you should find threads discussing this issue. I doubt the white oak from Ohio is appreciably different from any other, although there are dozens of sub-species of oak classified as "white" (rounded leaf lobes and acorns take two years to mature) and they're all lumped together for commercial lumber purposes.

By all accounts, sassafras is excellent for planking. Its rot resistance (heartwood only) is excellent and I think its physical properties are good. I've read that it was used for dugout canoes, although I've never seen a sassafras tree big enough for that purpose. It may split easier than most. It's not particularly hard, so I'm not sure how it would wear as a cockpit sole. Try the search feature for sassafras also.


Joe Sengl
06-25-2002, 11:37 AM
In Metamora, Indiana, there is a walnut water-wheel powering the millhouse. The walnut wheel replaced a wheel of poplar in 1993. The poplar wheel lasted for over 20 years. I believe facts like these can upset a million dollar government study. Although I had doubts about it's use, I have used sassafras on small craft for carlings, shear clamps and such with no problems. It's a tough but twisty kind of wood, smells great when working with it. I have outdoor furniture made with sassafras, left out for many years in Ohio, unprotected except for the first coat of latex paint when it was made, and the bare wood now has shiny spots where we sit our cans :cool: . Sassafras painted with googe or cpes would be pretty durable stuff.

Bob Cleek
06-25-2002, 04:16 PM
Norm's right. I've been using CPES for over twenty years, I'm sure. While Steve Smith has done all the scientific research (he's a Ph.D. chemist, I believe), I can remember dropping by his shop to get this or that (they make other stuff besides CPES) and he'd ask, "How's that stuff holding up, anyhow?" I'm sure he asked all the wooden boat guys that bought his stuff that same question. CPES was a "trade secret" in the wooden boat game for a long time. Smith and Co. manufactures INDUSTRIAL COATINGS, specialty stuff, a lot of which is custom made for some project or another. They didn't advertise and the internet didn't even exist. Somebody came along and cut some kind of deal to market CPES under the Rot-Doctor Restors-it label as a cure for rotten wood. Took big hunks of punky pier timbers and soaked them in CPES and put them on display in WestMarine and so on. Sure, you can soak just about anything porous in it and it will get sort of hard, but CPES was never intended to "restore" rotten wood. It was never intended to "encapsulate" wood (quite the contrary.)

CPES is a SEALER. Nothing more. It doesn't really matter how deep it soaks into the wood as long as it soaks in deep enough to hold on to it mechanically, which it certainly does. It forms a molecular bond with coatings and adhesives (paint, varnish and epoxy) applied within 36 hours during the cure period. (This is why it makes sense to use it when epoxy gluing... the epoxy adhesive is holding on deeper and harder to the wood it is "stronger than.") The biggest advantage of CPES is that it dramatically reduces peeling and cracking of paint and varnish resulting from water (not vapor) soaking underlying wood. Without it, water soaks into a joinery crack, like in a cabin side, when the wood works, soaks the wood around the crack and the varnish lets go and starts peeling up.

It isn't a miracle cure for anything. It just lets you varnish about a third as much. As for cost, it's a lot cheaper than the varnish it saves! A little bit goes a long way. It is about as thick as water and coats about the same as water soaks into wood. Thinning epoxy adhesive resins with alcohol or whatever is a second-best substitute and no cheaper. Thinned adhesive epoxy resin is a whole nother animal and not at all the same or as effective. CPES's solvents don't simply thin the epoxy, they dissolve resins and sap in the wood, permitting greater and more even penetration.

CPES is like crack cocaine... try it and you'll never let it go! LOL

06-25-2002, 04:22 PM
Thanks, Bob!

Wayne Jeffers
06-25-2002, 05:23 PM
Originally posted by Bob Cleek:
. . . , but CPES was never intended to "restore" rotten wood. It was never intended to "encapsulate" wood (quite the contrary.)

CPES is a SEALER. Nothing more. . . . Bob,

Perhaps you could share this insight with Mr. Smith. The principal focus of his company's web site is restoration of rotten wood, or to quote exactly, "The original Clear Penetrating Epoxy Sealer™ was developed for restoration of deteriorated wood." http://www.smithandcompany.org/ His site also features a link to http://www.woodrestoration.com/ which focuses exclusively on restoring rotten wood using CPES. I assume he endorses the content of that site, at least. This is the marketing claim that I find offensive.

My dictionary defines sealer as "a nonpermeable coating" or something used "to close completely as to make airtight or watertight." I think this is the meaning most people derive when they see the term "sealer." The product name itself is misleading. For the use you suggest, it would more accurately be called a primer.

As I said above, I believe you when you say CPES works well as a primer to ensure good bonding of subsequent coats, but this is not the primary focus of the marketing. And I've never heard an explanation as to why any other thin epoxy formulation would not work as well for this purpose, and at a much lower price.


[ 06-25-2002, 06:24 PM: Message edited by: Wayne Jeffers ]

06-26-2002, 05:48 PM

The person who is marketing CPES in Scandinavia is selling the product mainly to people who use it for repairing suspect or deteriorated wood in wooden constructions like houses. At least this is how I have understood it.

I donīt know how the business is going. I would assume that nobody in his right mind would rely on this method in order to give the strength back to deteriorated wood that is supposed to take important loads or that are vital parts of the construction.

However, wooden elements of lesser importance can brobably be succesfully treated with CPES as a means of avoiding unnecessary dismantling etc. I have used it myself in this way. Before I used it on my boat I made a test with a severely damaged peace of wood. It appeared that the liquid was soaked into the rotted part of the wood quite well, bringing the whole piece of wood back to its normal strength (more or less). It did not, however, soak into healthy wood to an extent of any practical purpose, except perhaps to act as a primer.

I donīt know if other comparable products, or regular epoxy glues with added solvents would perform in the same way because I havenīt tried them. It would be fairly easy to find it out. Iīm sure that any product or concoction should at least cure rather slowly in order to have time to penetrate before it cures. CPES is not a miracle penetrator if you compare it with e.g. linseed oil. But it certainly can bring bad wood back to life provided that the wood is bad enough and you know what youīre doing.

Wayne Jeffers
06-26-2002, 09:50 PM
Originally posted by Jorma Salomaa:
. . . It appeared that the liquid was soaked into the rotted part of the wood quite well, bringing the whole piece of wood back to its normal strength (more or less). It did not, however, soak into healthy wood to an extent of any practical purpose, except perhaps to act as a primer. . .

I can accept the testimonials that CPES works well as a primer, especially in problem situations. I expect other epoxies would do the same thing at a cheaper price.

I'm not sure what you mean when you say, "bringing the whole piece back to its normal strength (more or less)." Bringing back its strength in what respect?

There are a number of engineering measures for mechanical properties (strength) of wood, e.g., modulus of elasticity, modulus of rupture, maximum crushing strength, maximum shearing strength, tensile strength, etc. Which of these mechanical properties are restored to normal by application of CPES to "the rotted part of the wood?"

Have there been any independent tests done to measure any of these mechanical properties of wood that was once rotten, but to which CPES has been applied, to determine whether the rotted wood has returned to its normal (pre-rot) engineering characteristics?

I could even accept an assertion that CPES or any other thin epoxy applied to wood in the early stages of deterioration would impede future deterioration, perhaps markedly so. In the absence of detailed independent tests, I cannot believe that CPES applied to rotten wood will restore its original mechanical properties.


06-27-2002, 01:05 PM
An interesting point. Rotted wood varies in degree, from that where the rot might only affect a single fiber, to brown, crumbling powder and everything in between.

Does that stuff glue a single fiber or a few back to their neighbors? Many seem to think so.

Would it restore brown, crumbling debris? Certainly not. Nothing would.

Does it work sometimes? Many seem to think so. Can this be scientifically proven to be an exact thing, with guaranteed reproducible properties? I do not see how, for neither sound wood nor rotted wood is a reproducible thing. No one can make standardly rotted wood. I seem to recall the authors of that paper at www.woodrestoration.com (http://www.woodrestoration.com) said something to that effect, which is why they chose to test a surrogate standard, namely cedar. That is a pretty consistent material, readily available and reasonably reproducible, as their graphs and scatter-plots show.

It seems to me that the best that can be shown is circumstantial evidence for any material promoted as a restorative for wood with some variable degree of deterioration.

The anecdotal experiences of people using any product in an inexact field will show some pattern of circumstances where desirable results were achieved, and other circumstances where there were not satisfactory results. This testimonial evidence is circumstantial evidence, not proof, but a sufficient quantity of it can produce a compelling weight of belief that in some circumstances, some benefit may be derived.

Structural engineers have the same issue with partly deteriorated wood elements in buildings, on bridges and so forth. In such circumstances they cannot rely on probabilities or anecdotal evidence, and so they perform actual load-testing of the structural element. This can be done on a small scale, measuring a small beam deflection for a small weight. The deflection then shows important structural properties for that particular structural element.

In its own way, this individual testing of specific elements may become circumstantial evidence for some course of treatment, which may then become adopted. In a similar way, earthquake safety standards for buildings and elevated motorways evolve by tests of structures which failed and observation of structures which survive some particular earthquake. It would appear that the subject of wood treatment and restoration is evolving in a similar manner.

06-27-2002, 02:03 PM
I am going to use CPES on a 49 foot schooner I am building out of the local shore pine. I have read the rot doctors info and one thing missed in the discussion so far is that "the resins are derived from wood pulp, which gives them a toughness and flexibility approximating that of the original wood"(quoted from the rot doctor website). I wouldn't call the stuff a sealer but rather a wood stabilizer as that seems to be what it does mainly. I think the theory is that the size of the molecules from the wood oil is much more compatible with wood than the molecules from epoxy made from oil from the ground(the bilge of the world and we pump it up and spread it around). The fact that it allows water vapour to pass makes it ideal for boats. You can epoxy paint the outside to seal it and allow the inside planking to pass out moisture keeping that ideal dry rot habitat from forming.

Scott Rosen
06-27-2002, 02:15 PM
I've used CPES on rotten plywood in non-critical applications. I removed much of the "loose" material, but because of the location I had to leave some rotten wood in place. I saturated with CPES. Came back a week later and saturated it again. When it cured, the treated rotten areas felt as strong as the sound wood. I poked it with a marlinespike and it responded like sound wood. I prodded and pushed it and even gave it a few raps with a hammer. It continued to respond like sound wood.

Many moons ago, when I first discovered epoxy, I tried something similar with a low-viscosity epoxy. This was a horizontal surface, so I had gravity working for me in helping to pull the epoxy down into the rotten plywood. It was a failure. All that happened was the epoxy formed a layer on top of the rotten sections and pulled off easily--in one piece. It did not penetrate effectively. Because of that, I approached CPES with some doubt and skepticism.

I just completed a repair to my dinghy's daggerboard using CPES and Smith's Fill-It. I struck a rock last year and took a hefty chunck out of the plywood daggerboard. I cut away the loose wood, CPESed the end grain, and molded in a section using the Fill-It. I used waxed paper to get the shape and hold it in place during cure. After it cured, I tried to break it off and see if I could knock it loose. No go. It was indistinguishable from the plywood portion of the board. I know that's not exactly a precision test, but it was adequate for that particular use. Using the CPES and Fill-It was easier and quicker than cutting and fitting a graving piece and then shaping it.

Under the right circumstances, I would consider the use of CPES and Smith's FillIt in a structural repair, such as a rotten section of a frame. If done properly, I think it could work as well as a scarfed in piece of wood.

06-27-2002, 05:19 PM
Iīm afraid the only thing I can provide here is another piece of anecdotal experience. The particular piece of wood I was referring to in my earlier post was local Spruce (Picea abies), a piece of 6x4x57 cm, weighing 484 grams and having a moisture content of 6%. The wood was in an advanced stage of rot, meaning it was rotten from end to end but had enough of sound wood in order to keep it together. Itīs useless to try and describe it any more accurately. I made it stand in a shallow bowl filled with CPES so that the wood was immersed at a maximum of 1 cm in the liquid at any time. I poured in more liquid as it soaked into the wood. After two days I considered that it wasnīt taking up any more liquid. After that I sawed the wood in pieces to see how far the liquid had penetrated. There was appreciable penetration to a distance of 34 cm.

The weight of the wood developed as follows:

Start: 484 g
Day 5: 700 g
Day 7: 690 g
Day 11: 670 g
Day 23: 630 g
Day 105: 580 g
Day 120: 560 g
12 months: 530 g

Now I invite you to make your own conclusions. I can add that up till 25 cm from the base (which stood in the liquid) the wood appears as firm as sound wood.

I should also add that I made the test only for my own purposes and never anticipated to explain it in any detail to anybody. It should not be taken as an attempt to prove anything. It has only helped me to decide if, where and how to use the product.

[ 06-27-2002, 06:29 PM: Message edited by: Jorma Salomaa ]

Bob Cleek
06-27-2002, 09:45 PM
You're right, Wayne. I read Smith's site. I think the story grew in the telling. Now that my memory is jogged, let me add a bit of detail to the yarn.

As I remember it now, CPES was initially developed, perhaps in conjunction with research being done at the Army Corps of Engineers' South Pacific Test Facility at Sausalito. They had a big operation there testing all sorts of stuff the Corps used in the South Pacific. Don't ask me why they decided to test stuff for the South Pacific in foggy Sausalito, but they did. They would do weather exposure tests on paint and so on. Wood they shipped from the US for siding on barracks in Fiji or Guam and so on would be subjected to a whole new crew of bugs and borers and rot and weathering. CPES was developed, if memory serves, to answer the search for something that would keep it all together in the tropics. Smith developed it; not the Corps, but the original purpose as I remember it being told was to patch up funky architectural stuff. We are talking siding and ornaments, not heavy structural beams. I know one of its significant early uses in architectural applications was to seal and "restore" the exposed ends and tops of glue lam beams that had gone bad. (When glue lam came into vogue, a lot of buildings were designed with the glue lam beams extending out beyond the eaves. The ends weathered and rotted.) Paint stuck better with it, too. That was what it was about. I never remember anything about it being used to "restore" the strength to load bearing members or extensive chunks of punky wood like I've seen demonstrated in the "Rotdoc's" sales literature. To hear them tell it, you could take a bucket of rot and soak it in CPES and you'd have a new boat. That is pure crap. Whatever its true history, like I said, I've used gallons of the stuff for years and years and it is fantastic, so long as you don't expect more from it than it is capable of delivering. If wood is rotten, it ought to be replaced, not "restored." Only when that isn't feasable, or we are talking about a cosmetic fix, should CPES be used to "restore" it.

Wayne Jeffers
06-28-2002, 11:04 AM
Thanks, Bob. That's an endorsement that makes sense.

A question inspired by Jorma's last post: How long does it take CPES to kick at 75 or 80 degrees? If Jorma found it to wick up rotten wood a distance of 34cm, more than a foot, it must stay watery for a very long time before starting to kick.


06-28-2002, 03:12 PM
That was interesting, Bob. And I couldīnt agree more with the last two sentences of your post.

Wayne, I donīt know the exact curing time of the stuff. Itīs a bit hard to assess since in the beginning a lot of solvent evaporation takes place and it may seem that it starts kicking even if it doesīnt. I would say it fully cures in two days. We should ask Mr. Smith. And I think there are several varieties of the product, although Iīm not sure. In this part of the world it is sold by the name Lignu, and I faintly recall that it was called a "professional" version which cures somewhat faster (it doesīnt make sense, but as we know, professionals always seem to be in a hurry).

Anyway, I tried to record the progress of the penetration. Itīs a rough estimate since I could only observe the surface of the wood without knowing what was going on inside. This is what I wrote down:

10 minutes: 12 cm
30 minutes: 15 cm
1 hour: 19 cm
2 hours: 22 cm
4 hours: 26 cm
7 hours: 28 cm

After that nothing more seemed to happen.The final penetration of 34 cm was discovered only after I later cut the wood into several pieces.

Bob and Scott have probably used the stuff a lot more than I, so they might have something to say.

I use it to prime practically everything I paint or varnish, especially if the wood is old and has lost a lot of its natural resins on and close to the surface. I normally paint when the CPES is still tacky, within 4 to 6 hours, but at the latest within 24 hours. Interestingly, some oil paints can take more than a week to dry if I slap them on much before the 24 hours have elapsed.

Bob Cleek
06-29-2002, 12:28 PM
Okay... this may be helpful. A quote from the 1981 booklet: "How to Fix Your Wooden Boat, being #3 in a series of compleat guides for the able person, a vritable cornucopia of knowledge gleaned through the ages, selected by our panel of experts for most expedient rectification of the more common conditions of such craft... Extra added attraction: several delightful illustrations, pleasingly located throughout the text." Copyright 1981, Smith and Co. and with a title like that, ya just gotta love Steve Smith!

Now, this was written twenty years ago long before the Rot Doctor and others started hawking the stuff in their own cans as the cure-all for eveything from hang nails to hoof and mouth.

To quote Steve (with emphasis added):


CPES IS USED TO SEAL WOOD SURFACES prepatory to adhesive bonding, or to obtain higher bond strengths (in come cases, to obtain any bond at all). The sealer is particularly formulated to provide enhanced chemical adhesion to both epoxy resins and polysulfides. It provides a bond between microscopically rough wood surfaces and the adhesive, which is often viscous and cannot penetrate and saturate the microscopic fibers and spaces that make up the surface of the wood.


Most adhesives and paints are relatively viscous and will not penetrate past the loosened and roughened fibrous surface to attach themselves to the intact bulk of the wood. In fact, the loosely attached fibers at the surface tend to shield the underlying bulk of the wood from the wetting action of adhesives or coatings. The moisture and oils or saps in the wood can also act to prevent many materials from wetting the wood itself, just as oils in a concrete surface will prevent water from wetting the concrete. Resin systems which contain no solvents and which contain pigments, fillers, or thickeners will do a relatively POOR job of wetting and bonding to the intact bulk of the wood. (Comment: So much for the argument in favor of just thinning WEST System epoxy with alcohol or acetone for the same purpose.) However, FLEXIBLE epoxy adhesives with SPECIAL ADHESION ADDITIIVES applied to a FRESHLY CUT OR SANDED surface give excellent bonds to OILY or exotic hardwoods such as apetong, araki, and lignam vitae.

FOR THIS REASON WE HAVE FORMULATED the product we call CLEAR PENETRATING EPOXY SEALER. (Note: Apparently its original purpose was not to "restore" rotten wood.) It consists of an epoxy resin and a curing agent which, when cured, have a toughness and FLEXIBILITY COMPARABLE TO MOST WOODS. The CPES is formulated with the epoxy resins DISSOLVED IN A CAREFULLY SELECTED BLEND OF SOLVENTS DESIGNED TO DISSOLVE NOT ONLY THE WATER, BUT THE OILS AND SAPS FOUND IN WOODS. The wood is strengthened without making it excessively brittle, and NORMAL EXPANSION AND CONTRACTION OF THE WOOD WITH CHANGES IN TEMPERATURE AND HUMIDITY ARE ALLOWED.

AN EPOXY RESIN SEALER SYSTEM WHICH DOES NOT CONTAIN WATER-DISSOLVING SOLVENTS CANNOT PENETRATE WOOD AS EFFECTIVELY AS THIS SYSTEM. This is particularly apparent when repairing wood that has MILD dry rot. The CPES can be fed into an area, and it will migrate along the fibres of dry rot within the wood AS LONG AS IT CONTINUES TO BE FED IN.

The LONG WORKING TIME of this product (about 36 hours at 72 degrees F) means it will be very runny and RETAIN ITS MOISTURE DISSOLVING ABILITY FOR A GREAT LENGTH OF TIME. In one case we have heard of, the sealer was fed into a dry-rotted deck beam CONTINUOUSLY through a 1/4 inch hole, and six hours later began to drip out the far end of the same deck beam because the dry rot ran the entire 10 foot length. No other product available can penetrate and impregnate dry rotted wood so effectively.

In butt joints the CPES will also soak in great distances, so two or three coats several days apart may be necessary to completely seal the wood.

When two pieces of wood have been treated the day before with CPES, an adhesive will achieve the ultimate strength of bond between the two members. The sealer has provided a bond between the surface of each wooden member and the bulk of the wood itself. When applying a paint or varnish to wood, the durability of the coating will be exceptional becaue the paint has a strongly attached, chemically compatable surface to bond onto. Varnish applied over wood which has been treated with CPES has lasted more than three years (Comment: I can vouch for that!), whereas varnish on bare wood often peels in six to 12 months.

The two-component polysulfide rubber caulking and sealing compounds are among the best adhesives and sealants, but are so viscous they will not form a high-strength bond with bare wood. Yet when the wood has been treated with CPES a day or two before polysulfide caulking is applied, a very high strength, permanently waterproof joints are obtainable.


So, with a nod to Steve's copyright, that's what he has to say about CPES. Or at least had to say twenty years ago. It seems to definitively answer many of the questions raised in this thread. It was a pain in the ass to type it all out, but maybe it helps those who are new to the applications of this product.

[ 06-29-2002, 01:58 PM: Message edited by: Bob Cleek ]

Mr. Know It All
06-29-2002, 03:25 PM
This is a fantastic thread and I have learned much and I thank you all for your wisdom. I still have one question specific to my restoration project,a 1961 fir Plywood on oak frame Lapstrake hull. Where ,if anywhere, should I use CPES? I don't want to take the outside down to bare wood. There is already an epoxy based fairing compound filling all the imperfections in the strakes and If I sand all of that off I'll damage the top thin vanear of the 3/8" plywood. I've heatguned all the paint off but the fairing compound is stuck fast to the wood like a primer coat that won't come off. I figure why fight it. I've managed to expose the screw heads and clinch-nails and tightend and reclinched and replaced a few. Even if I could get the outside hull down to bare wood, would it be worth the trouble of applying CPES on a lapstrake constructed boat? Anything short of taking it all apart and you get no CPES in the lap joint where you need it anyway. I see the advantages of using CPES on the inside of the hull(it's down to bare wood and going to be painted and varnished) and parts that I'm replacing (the transom.decking and windshield) but how do I proceed on the outside hull and what can I use to seal the laps now that they're mechanically tight. It should be flexable since a lapstrake hull flexes and moves.Is 5200 a good option? OK....so I've asked more than one question. This is a 16 foot Lyman that will be used on weekends and stored on a trailer in the gar....uh...Boatshop. Any Ideas fellas?
Peace---> Kevin in Ohio

Wayne Jeffers
06-29-2002, 09:54 PM

I appreciate you taking the time to type that out. It probably contains more useful (and sensible) information about the product than I've seen in one place before. It seems to me far more useful than the information currently on Smith's web site.

Thirty-six hour working time certainly distinguishes it from any other epoxy I've heard of and would seem to support the claims of greater penetration.

Any suggestions on how much coverage to expect on old, but sound, western red cedar? How far could I expect to get on a 16' hull with a couple of quarts?


Regarding sealing your plywood laps: If everything is tight and she's not leaking, I'd hesitate to mess with it. If the laps won't take up, drastic measures may be called for of course.

A lot of people have a lot of unkind things to say about 5200 in such applications (because it can be too difficult to remove later, and perhaps for other reasons). I've seen a polysulfide such as BoatLife LifeCaulk suggested for this use. Robert Steward suggests 5200 for problem laps on page 195 of his Boatbuilding Manual, Fourth Edition, but he seems to make a less than enthusiastic endorsement of the process. It involves using a veiner to make a groove for the goo at the outside of the lap joint.


06-30-2002, 08:46 AM
Some more questions. Should a hull be painted within the 36 hour cure time period if the paint is not epoxy (alkyd)? Does CPES take the place of other primers? Also does an application of CPES take care of amine blush or should any underlying epoxy be washed down before applying it? thanks

Art Read
06-30-2002, 10:41 AM
Yes, as far as I know, ANY one part paint or varnish finish will benifit from going on before the cure. (I'd not wait much more than 24 hours though. Just my own personal prejudice) Can't say about "exotic", two part paints. You'd probably have to talk to the man himself about them. I've always just put red lead primer over the CPES then the finish paint over that. Maybe overkill, but it worked for me. Didn't use any "highbuild" primers or the like. Covered beautifully.

CPES itself won't have any amine blush to worry about, but it won't really do anything for you OVER already epoxied surfaces. It should be applied to bare, untreated wood in order to soak in at all and "bond" with the wood. You can apply "regular" epoxy over it with good result, but if you already have epoxy down, it won't be able to penetrate it. I doubt it could add any extra "bonding" properties over cured epoxy, but I'm not positive about that. Again, check with Mr. Smith. You're probably just gonna want to clean up the blush and paint any already epoxied areas as directed by the manufacturer.

(BTW... I'm from P-town. First house on the street on Commercial leading into town, across from the West end of the East end breakwater... Have you seen much of "HINDU" this summer? I used to run her. Still miss her...)

[ 06-30-2002, 12:03 PM: Message edited by: Art Read ]

Bob Cleek
06-30-2002, 03:07 PM
Some short answers... When it is being used as a sealer under paint or varnish, you really don't need to put on more than a single thick coat of CPES, like any other sealer. A 2 quart (half gallon) of it ought to do a 16' boat easily. It seems to spread forever. It goes on about like slapping paint thinner would. It has that consistency.

If you have residue other coatings on the wood, I'd just put CPES on top of the prepped wood. It isn't as effective as putting it on new wood, but still, it keeps the new paint sticking. HOWEVER, the solvents in it will soften just about anything, so expect the CPES to possibly lift old paint. If so, just let it harden and sand fair. The old paint will get painted over anyhow. As for Bondo or some other fairing compounds, test it first.

Yea, CPES is worthwhile even on top of stripped wood or on a hull where you can't get it in everywhere. Its ability to keep paint and varnish sticking will still be worth it.

paul oman
07-03-2002, 08:41 AM
why not make your own penetrating epoxy using a thin high quality epoxy and your own solvent? Ask for the MSDS sheet on CPES and check the % list of solvents and epoxies used.

Mix up your own blend of solvent and epoxy (or use any of the commerical products out there). Place a layer in a dish -say 1/8 - 1/2 inch thick. Observe how rubber it is when cured.

Is the bond to a rubbery (chemically damaged) epoxy stonger than the bond of a good coating (or epoxy) to the firm and hard wood? Good question, I do not know, but something to consider. Perhaps giving the wood a good profile (roughness - lots of surface area) is the best answer. Also, I suspect that plywood might have a 'film' on it due to manufacturing and that it should be 'cleaned' off to get a good bond. A solvent rich penetrating epoxy might do the job here, but it would be the solvents doing the work (of prepping and cleaning the surface for strong adhesion to topcoats), not the epoxy.

www.epoxyproducts.com (http://www.epoxyproducts.com)

07-04-2002, 10:20 AM
Originally posted by paul oman:
why not make your own penetrating epoxy using a thin high quality epoxy and your own solvent? Ask for the MSDS sheet on CPES and check the % list of solvents and epoxies used.

Mix up your own blend of solvent and epoxy (or use any of the commerical products out there). Place a layer in a dish -say 1/8 - 1/2 inch thick. Observe how rubber it is when cured. <snip>That's not good science, Paul.

If you have a better product to offer, or an actual formula that you can show works, then you should produce it. That would be better science.

There is an open standard for such products at www.woodrestoration.com. (http://www.woodrestoration.com.) If you have some disagreement with it, or have something better, you could do your own science and publish it, and get architects and structural engineers to recognize yours. That would be better science.

To say that something might be better, and invite others to discover it, is only saying that you can't come up with something better, which doesn't help anyone, even you.

Any product can be tested in a way that is wrong for that product, and then the claim made that the product is deficient. That is a basic propaganda technique, The Argument by False Analogy. That is VERY bad science. It seeks to discredit something by a lie. That is one manifestation of evil.

I could show that painting West System epoxy on canvas gave a brittle finish and the canvas cracked and failed soon, and then claim the WEST epoxy product was trash. It would be unethical of me to do that, for it is an incorrect use of that product, which is perfectly fine for laminating hickory or other woods of comparable stiffness, or for layup with glass fibres in certain circumstances.

You have offered as a valid test of a product designed to impregnate a porous medium and then cure after its solvents have evaporated out of that material, the test that it be allowed to gel in a rubbery mass with its solvents entrained. That is what I described a few paragraphs earlier.

No paint or coatings manufacturer intends its products be allowed to gel in a puddle a half-inch thick, and yet you state that is how such a product ought be evaluated.

That is not only bad science on your part, it is advocating bad science on the part of others.

Please don't do that. It lowers everyone's ability to know, and to think accurately, and to do things that actually work. It lowers the intelligence of others, and to that extent lowers the quality of their survival. It is not help.

[ 07-04-2002, 11:21 AM: Message edited by: thechemist ]

07-04-2002, 10:59 AM
Art, thanks for the tips. Yes the Hindu is still around, I just saw her in the harbor, very beautiful schooner. Her owner, John Bennett, just pased away a couple of weeks ago. They had a memorial and viking funeral (his cremated remains set out on a flaming dory) last week.

Art Read
07-04-2002, 02:42 PM
Doug, I was just "chatting" with my sister online about her new boat. (see the Lyman thread) She told me about John. She's in P-town now and says HINDU is out sailing as we speak. I wonder who's running her? I worked with John quite a bit after he bought her, but the "business" was never the same after her old owner/skipper, Justin retired and sold her and the whale watchers took over the wharf... I'd probably still be there otherwise.

This makes the third, former skipper of HINDU to pass in my memory. At least John was striken while sailing her. Hope it's not a "trend", I'm the only I know left! Still, that's how I'd like to go... sailing aboard a boat I loved. My folks were on hand for the "viking" funeral. I just hope that was a "tired" dory they burned... I understand he once said he wanted to have it done with HINDU herself! I hope he was joking, and am glad that "cooler" heads prevailed. I suspect that Susie, the old owner's daughter would have chained herself to the deck if they'd tried.

Any idea what's to become of her? If you hear anything, let me know.

Happy fourth!

Paul Brooks
07-08-2002, 06:59 AM
On the use of CPES / epoxy. I've just finished fitting the cabin sides / cockpit coaming - about 16ft of 1in by 6in Iroko. This has been epoxied and screwed in place. I want to finish them bright, but my previous experience of using epoxy (West's) as a base for varnish has not been a happy one. It always seems to pick up bubbles or marks and is generally difficult to get smooth. Do you think CPES plus varnish would be OK or do you think that the extra moisture through varnish / CPES versus varnish / epoxy will cause movement / cracking in the wood?

Bob Cleek
07-08-2002, 12:19 PM
Come on, Paul, read the thread! The short answer is yes, CPES IS DESIGNED for use under varnish!

Paul Brooks
07-08-2002, 02:14 PM
That wasn't my question. I know that CPES is an excellent base for varnish. Perhaps I should have worded it differently.

Hopefully, this is more understandable. My question was: CPES allows moisture in / out while epoxy allows very little moisture. So will I see significant wood movement using CPES versus epoxy - or is the potential movement not worth worrying about.