Alternatives to clear penetrating epoxy?

[johnw]

I used Smith's clear penetrating epoxy on Black Swan, and it has worked well in keeping the plywood from checking, but I hate working with the stuff. Any other recommendations for keeping the plywood on the new boat from checking?

[David G]

Fiberglass (or other fabric) and epoxy. I've had success keeping fir plywood from checking with as light as 2 oz. e-glass set in epoxy.

[wizbang 13]

is Black swan fir?
If the new boat is okume, a regular good paint job with regular paint?
hard to believe myself, but apparently some do not slather their boats with epoxy.
Seen Flying Clouds paint job on Best paint thread? 16 gallons of penetrol!! (Po Cedar )

[johnw]

Black Swan is okume, as will be the new boat. I've already bought the lumber.

[Bob Adams]

I use a poor man's Smiths, just whip up some WEST and cut it with a touch of xylene (lacquer thinner). Penetrates well, but if it's the smell that puts you off, this may not be much of an improvement.

[johnw]

Yeah, it's the smell. I can stand it, but do I have to? If there's something that works just as well, why not go with that?

[johnw]

From this, http://www.seqair.com/skunkworks/Glu.../Thinning.html

it looks like you can thin epoxy with denatured alcohol, which should be easier to tolerate than whatever they use in Smith's penetrating epoxy. Has anyone tried it?

[Bob Adams]

I use denatured achohol for clean up....I never thought to thin with it. According to your link, you can and it certainly would be easieron your nose.

[Jim Ledger]

You don't want to use Smiths without a respirator, it will make your kidneys ache and cause dark clouds to gather over your head.

With a respirator there is no objectionable odor.

[johnw]

You don't want to use Smiths without a respirator, it will make your kidneys ache and cause dark clouds to gather over your head.

With a respirator there is no objectionable odor.

My objection is not just to the odor, it's to the fact that the odor is made by something likely to damage my body. Denatured alcohol can't possibly be as poisonous.

[JimConlin]

You've gotten good advice.
On okoume, ordinary paint systems are fine.
On fir ply, use light glass in vanilla epoxy. Warmth helps.

[Frank R]

Don't thin epoxy. Real research has shown that is not the best: http://www.westsystem.com/ss/thinnin...-system-epoxy/

Other brands of epoxy have almost no odor and are cheaper too. I never have to wear a respirator when using epoxy.

From http://www.westsystem.com/ss/underst...-overexposure/

"Exposure by inhaling vapors is unlikely, because epoxy products evaporate slowly. However, the risk increases when ventilation is inadequate or when the products are heated."

[Jim Ledger]

My objection is not just to the odor, it's to the fact that the odor is made by something likely to damage my body. Denatured alcohol can't possibly be as poisonous.

Any solvent is going to be bad for your health. but once you put on the mask you're good to go. It's always good to use a sealer under any paint system, and a two-part epoxy like Smiths is hard to beat.

[Lew Barrett]

Any solvent is going to be bad for your health. but once you put on the mask you're good to go. It's always good to use a sealer under any paint system, and a two-part epoxy like Smiths is hard to beat.

John: apply large runs of epoxy with a proper respirator and none of it matters, just as Jim says. Otherwise, prepare for aromas that are not as pleasing nor healthful as bread in the hearth. Lord knows what we've all done to ourselves over the years, but it can't be pretty!

[johnw]

MAS "Medium cure epoxy," warm it up separatly with a heater before mixing, it will penetrate any wood, and work fine.
Let it get hot, mix it and lay it down. No amine blush afterwards.

How hot, and how long before it sets up?

[James McMullen]

John, I hate CPES! Won't allow it in the shop. Too fracking toxic!

Any standard boatbuilding epoxy will work fine--West System, MAS, System Three. I prefer System Three Silvertip resin for use here in the PNW as it seems to be the most damp and cold tolerant of them all, but it doesn't really matter. Any of them you can use the heatgun trick on to get it to soak in and go superfluid when it reaches that certain temperature, and without all that noxious volatile solvent destroying your central nervous system.

CPES is for people with a deathwish. Seriously, it is nastier than bottom paint or two-part polyurethane. Dreadful stuff.

[SMARTINSEN]

You don't want to use Smiths without a respirator, it will make your kidneys ache and cause dark clouds to gather over your head.

John, I hate CPES! Won't allow it in the shop. Too fracking toxic! CPES is for people with a deathwish. Seriously, it is nastier than bottom paint or two-part polyurethane. Dreadful stuff.

Out of curiosity, how do these statements reconcile with this info on the MSDS from Smiths?

Respiratory Protection: None with normal use
Ventilation: Local exhaust usually adequate
Protective Gloves: Recommended for sensitive individuals
Eye Protection: Safety glasses or chemical goggles to prevent eye contact
Other Protective Equipment or Clothing: None

from:
http://www.jamestowndistributors.com/userportal/pdfs/MSDS/Smith_and_company/CPES_PART_A_and_B.pdf




ETA: Here is an earlier discussion on fumes.http://forum.woodenboat.com/showthre...are-CPES-fumes

[Lewisboater]

Someone beat me to it.

[James McMullen]

Who ya gonna trust? The people in charge of selling the stuff or the poor schmoes who actually had to apply it? Look, I work with far more toxic chemicals on a daily basis than I ever would prefer, and I got to tell you that Smith's CPES is less fun than red lead and Awgrip stirred together. It totally sucks.

"Local exhaust usually adequate" is a bald-faced fracking lie!

[PeterSibley]

Probably not applicable but these days I seal plywood with water base polyurethane, I haven't used it on a boat yet but it is great stuff, low build and extremely water resistant . Any comments from real boat builders?

[David G]

Probably not applicable but these days I seal plywood with water base polyurethane, I haven't used it on a boat yet but it is great stuff, low build and extremely water resistant . Any comments from real boat builders?

Dries harder than spar varnish (that's good). Also dries much more brittle (that's very bad). Also likely has no UV protection built in (that's also bad). The second item is enough to eliminate it from a marine application.

[Binnacle Bat]

I skimmed the West advisory linked to above, and one thing occurred to me. They said it didn't matter how far the epoxy penetrated, only the permability of the barrier mattered. I have very little experience with epoxy, but I have seen a lot of dings in varnish turn into a variety of white or black scars in the wood, requiring stripping, sanding, bleaching staining etc. to get a uniform surface to reseal with whatever.

It seems to me that the more you can get the epoxy to soak into the wood, subject to the wear and tear of the real world, the better protected the wood will be, and that a few mills of the best goop in the word over a relatively soft wood don't count for **** when a tired old guy is getting klutzy deploying the anchor, unstepping the mast or whatever.

Any thoughts from the experts?

Allan

[PeterSibley]

Dries harder than spar varnish (that's good). Also dries much more brittle (that's very bad). Also likely has no UV protection built in (that's also bad). The second item is enough to eliminate it from a marine application.

I've been using it to seal casting patterns and for that it does a very good job. Re UV resistance ... epoxy isn't either ? I agree that it's extreme hardness would be bad on anything that might move .

[Eric Hvalsoe]

Pathetic. Almost no non epoxy responses. The answer is simple, Pettit Old Salem clear sealer. It has a strong linseed oil base aroma, although I don't really understand what the drying agent is - the stuff does flash off fairly quickly under the right conditions. For conventional primer, single part urethane or oil topcoats. I would not topcoat it with an epoxy product. Been around forever.

That MSDS from Smith's is BS. It goes under the trade name Restore It at Fisheries. Maybe Xylene is the active solvent. Respirator only in confined spaces, without adequate ventilation the space will reek for days. Outdoors still keep your nose out of it. I sometimes use it anyhow - when I'm going hardcore, when I want something sealed and dry NOW, using the cold weather forumulation.

[johnw]

Thanks, Eric. I'm building outdoors, and I do have some Smith's left from my last project, so I suppose it's still an option, but I'm leery of it. Having used it is what made me not like it.

Can't think of a time when I've been displeased with anything from Petit, though mostly I've just used their paints.

[RodB]

I doubt much beats the total performance of CPES for what it does. . . unless you epoxy coat or epoxy glass the panels. From personal tests, I do not think thinned epoxy performs anything like CPES when applied to wood. The times I use CPES it does it's jobs admirably without having to coat with standard epoxy, and I tend to use it in specific situations.

Example... 15 year old teak and holly floor panels dried out after a 30 day soak when a boat was flooded. Dried out the panels well, treated with quaternary ammonium compound for mold, let dry for a couple weeks... applied CPES till it would not soak in any more... (mostly to the end grain and bottom surface) ...applied Daly's Profin, which was the original finish that had lasted over 15 years. My job was to refinish the panels removing stains etc and clean up the mold growth between the panels and the fiberglass liner of the hull etc. The CPES was a very worthwhile step in this restorative process especially for the location for these plywood veneer panels. The added insurance from using the CPES was certainly worthwhile IMHO. I would't have considered anything else except I did consider applying ethylene glycol to the pourous bottom surfaces... but ended up leaving that step out.

I work with CPES in open areas with a breeze or fan...

RodB

[Lew Barrett]

Pathetic. Almost no non epoxy responses.

C'mon Eric! Don't hold back!

Query: Old Salem is marvelous stuff, but isn't it much like thinned varnish?

[Bob Cleek]

Sissies! The CPES MSDS is accurate. Those have to be vetted by an independent reviewing agency, IIRC. Its solvents do have an aroma that some find unpleasant (or otherwise find scarey) and all solvent based coatings should be applied in well ventilated areas. I've applied gallons of the stuff with no respirator and no ill effects. Come on, you're working outdoors. If the smell bothers you, simply get a big fan and direct the air flow so the wind blows the fumes away. That way, you'll never notice it.

Everybody used Old Salem and similar seallers before Smith came out with CPES, which has pretty much replaced it entirely. There are lots of ways to seal wood, but, frankly, the general consensus in the trades is that nothing does the job as well as CPES. (But, no, it doesn't "restore rotten wood" and it isn't some miracle cure. It's just a very effective penetrating sealer for use beneath other surface coatings.) CPES isn't at all the same as simple thinned epoxy resin at all. It's an entirely different coating system. What "penetrates" with thinned epoxy resin is pretty much only the solvent you use. The epoxy resin ends up as a thin coating on the surface (which is why WEST says, "What's important is the impermeable barrier.") The epoxy in CPES actually penetrates into the wood fibres, rather than sitting on top of them, making the surface of the wood itself "impermiable." That's the difference and that's why it works better. (And why it was invented to stabilize decayed architectural embellishments on old Victorian gingerbread buildings.)

[keyhavenpotterer]

This is a system I've not tried but it may have merit.

Soak the plywood in Varnol oil. As much as it will take, repeatedly till it takes n'more. This fully fills the outer plywood ply in hydrophobic oil and brings out nice grain with mahogany. It also pushes any air out of this outer veneer so that step two which is to coat it in Schooner Tung oil varnish doesn't lift off in the heat. The tung oil varnish sticks to the oil based varnol. I guess the oil also slows heating of the wood. Chris Perkins takes this approach with his own boats and has had success with it, but I've not tried it.

MAS do a low viscosity resin. I've not used my pot yet, but MAS epoxy seems smell free so far.

Ed

[skaraborgcraft]

i have never used cpes. I have used a lot of single part G4 polyurethane sealer (made by Bondaglass Voss)....though thats a bit smelly too, dont even know if you cant get that Stateside? Fast drying (moisture curing),high build,excellent base for varnish/paint.

[pcford]

C'mon Eric! Don't hold back!

Query: Old Salem is marvelous stuff, but isn't it much like thinned varnish?

I tend to agree with Eric...I did a repair on a transom and had to do it with using dutchmen...soaked it up with Restore It...(that's actually the name on the can though people tend to use CPES here...maybe because Restore It sounds too "miracle product." Like Eric I do believe it is a good sealer...Do I use it religiously...nope. Certainly not like our brethren down in the Bay Area do.

Old Salem sealer is not thinned down varnish...You can get a couple coats on in a day and follow up with a varnish coat the second. Many yards in Seattle have used it.

[James McMullen]

paraphrased: "CPES is great!"

Did we really just witness the Cleek endorsing an epoxy product? Seriously?!?

I told you this stuff is from the Devil!

[pcford]

Did we really just witness the Cleek endorsing an epoxy product? Seriously?!?

I told you this stuff is from the Devil!

Anyone who owns a wooden boat between Mendocino and Monterrey is obligated to use the stuff, McM. It's the law.

The Devil indeed.

[NickW]

John

Here in the UK, the following is quite well thought of http://www.connexiontechnology.co.uk...k-wood-mk2.pdf . It has had good write ups in Watercraft for ease of use and being water based is of low toxicity. As it is manufactured by a French company http://www.sicomin.com/home.aspx , it appears to be only available in the Europe and French colonies, but may well be avilable in Canada (Quebec).

Nick

[johnw]

John

Here in the UK, the following is quite well thought of http://www.connexiontechnology.co.uk...k-wood-mk2.pdf . It has had good write ups in Watercraft for ease of use and being water based is of low toxicity. As it is manufactured by a French company http://www.sicomin.com/home.aspx , it appears to be only available in the Europe and French colonies, but may well be avilable in Canada (Quebec).

Nick

I've never seen the stuff around here, but I'll look around.

[johnw]

Did we really just witness the Cleek endorsing an epoxy product? Seriously?!?

I told you this stuff is from the Devil!

Now I know the world is ending.

[RodB]

Bob.... thanks for clear concise comments, with which I agree completely based on personal experience and the literature I have read.

RodB

[johnw]

I tend to agree with Eric...I did a repair on a transom and had to do it with using dutchmen...soaked it up with Restore It...(that's actually the name on the can though people tend to use CPES here...maybe because Restore It sounds too "miracle product." Like Eric I do believe it is a good sealer...Do I use it religiously...nope. Certainly not like our brethren down in the Bay Area do.

Old Salem sealer is not thinned down varnish...You can get a couple coats on in a day and follow up with a varnish coat the second. Many yards in Seattle have used it.

Do they use it to seal plywood?

[willin woodworks]

The first time I saw the letters CPES was in a Cleek post; had to be close to fifteen years ago? If theres a better sealer or primer for varnish I haven't found it. As Bob says it's so much more than thinned epoxy. Does a great job of sealing the cores in FRP decks when replacing or rebedding hardware. I am convinced that you get a superior bond wood to wood, especially endgrain if you prime an epoxy joint with CPES. It seals plywood engrain up tight and the penetration is impressive.

I dont like the smell either so I move upwind or ventilate the shop. Unless you're drinking the stuff or letting it cure on your skin it ain't gonna hurt you.

[BrianM]

From this, http://www.seqair.com/skunkworks/Glu.../Thinning.html

it looks like you can thin epoxy with denatured alcohol, which should be easier to tolerate than whatever they use in Smith's penetrating epoxy. Has anyone tried it?

My homebrew includes thinning laminating epoxy with:
3 parts Xylene
1 part Denatured Alcohol

Blend really well.

There should be no "Smell" as you should be wearing a Charcoal Activated Respirator all the time. You need to also keep all that crap off your skin all the time. Work with it, but work smart.




Dig into the Forum archives and you will find a couple of clearly written formulas of "Thinning" epoxy that give you the characteristics you want.


My homebrew stabilizes the wood and produces an excellent surface to paint or varnish. Solvents slow down the curing process of epoxy, and allow the molecules to migrate more deeply into the cellular structure of the wood. Some solvents make the epoxy cure in a "sponge-like" matrix (i.e. it is porous). This allows subsequent treatments to travel through those pores so eventually you have a semi-solid epoxy barrier, but it is DEEP in the wood rather than just sitting on top like un-thinned epoxy..
Some solvents will make the epoxy "rubbery" once cured. You may, or may not want this characteristic.

Experiment with the Xylene and Denatured alcohol ratio and see what works best for your application.

[Paul G.]

What "penetrates" with thinned epoxy resin is pretty much only the solvent you use. The epoxy resin ends up as a thin coating on the surface (which is why WEST says, "What's important is the impermeable barrier.") The epoxy in CPES actually penetrates into the wood fibres, rather than sitting on top of them, making the surface of the wood itself "impermiable." That's the difference and that's why it works better. (And why it was invented to stabilize decayed architectural embellishments on old Victorian gingerbread buildings.)

That does not make any sense, CPES is thinned epoxy with the Colonels secret recipe of solvents. If the epoxy is dissolved in a solvent then it will travel into the wood fibres with the solvent. The longer it takes to go off the deeper it will penetrate. There is a certain point where the epoxy wont set up but apart minor differences in the epoxy and varying the solvent ratio's to suit I really cannot see how CPES is any more than a well marketed way to sell very cheap solvents for a very high price.

My own experiments have illustrated how far my versions of epoxy sealer will penetrate using xylene or meths or proprietary epoxy paint thinners. Eventually every brew goes off, some rubbery and some hard but more solvent equals greater penetration and it doesnt seem to matter a great deal which solvent is used.

Considering that CPES is just a sealer and will be overcoated, then the final coating play a far more important role than the porous sealer. I have also used warmed neat epoxy as a primer for varnish and it worked extremely well. No epoxy wondermix will penetrate very deeply into side grain so I think the main advantage for a thinned epoxy "sealer"coat on side grain is that it doesnt run and provides a smooth easy surface to sand for the next coat of whatever.

sales blurb

This is the base product for any wood rot repair. Applied liberally, it will penetrate dry-rotted wood and go into the first layers of good wood, discouraging and encapsulating rot fungi and restoring the soft wood to structural strength. Other chemical products may put a temporary stop to wood rot, but only a premium epoxy can give long-term solutions, restore strength and endure under extreme environmental conditions. All epoxy products are not the same. Most are made from petrochemicals. "Clear Penetrating Epoxy Sealer" (CPES™) is substantially made from wood itself and these particular resins when cured, will have a toughness and flexibility that is comparable to the original wood. (CPES™) contains a feature which dissolves moisture in wood. Try bending cured epoxy products by other names-. (Wear safety glasses.) Premium epoxy products must flex as wood will, under different regional weather conditions. This product is also one of the best primers we have ever seen and applies to any type of coatings. If you are tired of getting paint to stick and last, (CPES™) is your cure. (CPES™) allows wood to breath and is a 1:1 mix.

"Clear Penetrating Epoxy Sealer" (CPES™) is substantially made from wood itself" That does not make any sense to me, they are referring to wood alcohol perhaps?

"(CPES™) contains a feature which dissolves moisture in wood." Meths will absorb water and evaporate it

"Try bending cured epoxy products by other names-" My experience is that any solvent added in the right amount will make epoxy rubbery

"(CPES™) allows wood to breath" absolutely, thinned epoxy is full of microscopic holes, again any thinner will do this.


I am sure that CPES is a good product perhaps the ratios etc are worked out well, but my own brews are fantastic primers, penetrate extremely well and display all the properties advertised above but I can make them myself for a fraction of the cost of a proprietary product.

[Tom Painter]

Reuel Parker talks about using epoxy thinned 15% with "equal parts methyl ethyl ketone and toluene" as a sealer in his cold molding book.

[RodB]

Paul G.... I wonder if you have bothered to review the wood restoration studies that Smith and Company show the link to see how CPES works.

http://www.woodrestoration.com/

I will cite a personal example... when considering restoring an old woody Lightning (which we decided to pass on) we noted that much of the wood in the interior (deck framing, carllns, etc) was very dessicated and quite less in weight than healthy wood. Although lighter in weight than healthy nromal wood, it still had a decent amount of strength deduced from trying to break a longer piece. The wood was most likely very very dry and partially degraded (oxidized and perhaps exposed to organisms) ) over many years sitting in the Texas summers. We sawed off a few chunks of this material (really small 6 inch chunks of 1x2 material for all practical purposes). Two of these pieces were saturated with CPES until no more would soak in.

Once cured we cut one of these pieces in two and found the entire matrix of the core had been saturated with CPES and the interior of these test pieces looked "plasticised" more or less. Although this degraded wood was quite light, after treatment with CPES it was absolutely stabilized from our visual inspection. I know from personal experience that thinned epoxy (acetone, MEK, Naptha) would not have resulted in the same uniform solid matrix within the body of those pieces of wood. Just from a visual inspection and messing around with this test sample, it was quite obvious that the sample had been converted into a much more "solid" piece of material with cured CPES filling all the cells. In my experience, using solvents to thin epoxy is quite different in that the solvents flash off and you are left with voids and irregularly shaped solids... and not necessarily a formed solid matrix.

CPES if applied on a sealed surface or some other material will dry shiny and will have some volume... so even if some solvents flash off, there is enough solids left to fill voids and coat surfaces well with a strong material.

This link simply explains why the CPES soaked so far into the test pieces above.
http://www.rotdoctor.com/test/penetration.html

Reuel Parker talks about using epoxy thinned 15% with "equal parts methyl ethyl ketone and toluene" as a sealer in his cold molding book.

A retired judge in the Houston built a Reuel Parker design with a hull that had an interior layer of tongue and groove Doug fir and two additional layers of 1/4 ply cold molded on the exterior of the hull. The interior was completely soaked with thinned epoxy until no more would soak in then primed and painted with two part linear polyurethane. Later when this project was more or less abandoned, a 7 year period passed by (till I saw the boat) and because the boat was not covered well it had solid water enter the boat now and then with the high humidity of central coastal Texas and of course plenty of oxygen. The rot that took place in that interior surface of the hull was scary.... and of course the tongue and groove layer acted like a bunch of straws moving the water from the entryway towards the bow. The entire cockpit floor had to be removed and much of one side of the cockpit seats and a compartment under the seat that entered the cabin as part of a large ice storage box that was half in the cabin and half in the cockpit. Bottom line... I'd never even consider using thinned epoxy for much of anything. Now, CPES, thats another matter.



RodB

[johnw]

Well, you can abuse pretty much any boat enough to destroy it. All I want is a good enough sealer that the ply won't check if I keep it painted and treat the boat reasonably well.

I still have two questions. Will Old Salem work as well as CPES or thinned epoxy, and can anyone tell me why CPES has any claim to be better than thinned epoxy? I'm pretty sure that the smell/kidney damaging stuff I'm objecting to is toluene or something equally foul, and I'm wondering if there is a particular advantage to this over less dangerous thinners like alcohol. RodB sounds pretty persuasive on this, but I'd like to know why it performs better than other forms of thinned epoxy.

[RodB]

In case you missed this...

Per Bob Cleek: The epoxy in CPES actually penetrates into the wood fibres, rather than sitting on top of them, making the surface of the wood itself "impermiable." That's the difference and that's why it works better. (And why it was invented to stabilize decayed architectural embellishments on old Victorian gingerbread buildings.)

RodB

[Paul G.]

I think you have to compare apples with apples on thinned epoxy.CPES is a consistent formula, while homebrews vary greatly. CPES will not create a solid matrix any more than correctly thinned epoxy. The fluid still has to travel in to the voids to fill them, and a dissolved epoxy is entirely dependent on the solvent to transport it deeper into the timber. There is no magic ingredient unless you think the "mostly wood" bull from the advert actually means anything.

For all intents and purposes to seal some ply all I would do would be to buy a litre or two of xylene and mix it about 10-20% with some west and paint it on-end of story! The CPES thing has a hint of snake oil to it but to be fair I have not tried it myself. I have used proprietary sealers of the same type, one being good old everdure with the fungicide in it and the other an Ados brand epoxy sealer. Instructions were the same, keep painting until it doesnt absorb any more and goes glossy!

For a painting substrate one coat of thinned epoxy is fine. But if you want to throw money away on the bought stuff, I really dont see any difference apart from a confidence that comes from a label.

[johnw]

In case you missed this...


RodB

Didn't miss it, I just asked why this would be the case with CPES and not with thinned epoxy. Is there some substance in it that is not in thinned epoxy? If so, what is it, and why does it make CPES work better? I'm not a chemist, and I don't have as much experience as a lot of people around here, I'm just trying to wrap my brain around the information.

[Paul G.]

Furthermore, I think we have moved on from thinned epoxy generally in boatbuilding. Its a leftover from polyester days when thinning did something. Why on earth would you spend hard earned dollars on a product that isnt waterproof, does not add any significant strength and is generally inferior in every way than straight epoxy? Clearly the best way to avoid rot is to not build water traps, use ventilation, or FULLY seal the timber in neat epoxy!

I have given up on adding solvents and now just warm the resin and paint it on. That way you get maximum adhesion, waterproofing and an excellent substrate for painting. Thinned epoxy absolutely needs a paint or neat epoxy covering system in a wet area, down here in NZ plenty of boats have all the not seen bits painted in neat epoxy- no other paint required. I would not do that with thinned epoxy of any sort.

I have used it thinned as a primer, but to be fair its more of a feel good factor when I have some spare resin mixed up and I want to get rid of it and Bingo Ill paint the stuff on somewhere!

[Paul G.]

Didn't miss it, I just asked why this would be the case with CPES and not with thinned epoxy. Is there some substance in it that is not in thinned epoxy? If so, what is it, and why does it make CPES work better? I'm not a chemist, and I don't have as much experience as a lot of people around here, I'm just trying to wrap my brain around the information.

For your job, ideally use neat epoxy warmed and rolled on, lightly glassed if you think its really going to check, or get decent marine ply with a nice veneer and just paint it!

Is thinning necessary?
There is a perception that epoxy needs to penetrate deeply into wood to be effective. Sometimes this is true, but most of the time it is not. Some common misconceptions are that deep penetration of epoxy 1) makes rotted wood as strong as new, 2) increases adhesion, and 3) makes wood more waterproof. The following is a brief discussion of these points.

1) Rotted wood impregnated with epoxy does not make the damaged wood as good as new. Deep penetration of epoxy into rotted wood will make the wood hard but it will not restore its original strength. This is not important if the rotted material is non-load bearing. A rotted door threshold does not need to be strong, just hard. However, when the wood fiber is damaged, wood loses its ability to carry loads and unless the fiber is replaced, it will not regain its full strength. A rotted deck beam or sailboat mast needs more than epoxy consolidation to return the wood to its original load carrying capacity.
2) Adhesion in all but the highest density wood is not enhanced by deep penetration of the glue into the wood. Research performed at the Forest Products Laboratory showed that adhesion to birch was increased slightly by using thinned epoxy. In lower density wood species like Sitka spruce or Douglas fir, the weak link is the cross grain strength of the wood. It does not matter if the epoxy penetrates l/4" into the wood or 0.005". The strength of the wood, the amount of surface area and the adhesive ability of the glue determine the strength of a glue joint. Most types of wood glue do not penetrate deeply, yet, if used properly, they can exceed the grain strength. Epoxy is no exception.
3) Water resistance of a piece of wood is not enhanced by deep penetration. Wrapping wood in plastic makes a pretty good waterproof seal without any penetration at all. Likewise, an epoxy coating on the surface is more water-resistant than a thinned epoxy coating that has penetrated deeply into the wood because, in most instances, the epoxy thinned with solvent is porous.

from http://www.seqair.com/skunkworks/Glu.../Thinning.html

[RodB]

Paul G....

Your quote about thinning epoxy misses the point. CPES was developed to infiltrate and stabilize problematic wood and to be a sealer with the ability to act as a moisture barrier. It also offers a surface that allows for a very strong adhesion to paints and varnishes... so while acting as a sealer it also acts as a very good primer. CPES is a very low viscosity epoxy... not just a solvent thinned epoxy. It also has some ingredients that are akin to the resins in trees.

Companies such as Gougeon Brothers and System Three have tried to come up with a similar product because CPES has some very specific uses and is a money making product because of its capabilities. The quote you posted above is not relevant to a product (CPES) that has very specific capabilities... that does not necessarily fall into the category ... "solvent thinned epoxy". I have seen the effect of a totally infiltrated piece of wood with CPES... it filled the cells and gave the appearance of a "plasticized interior". I am convinced I could not have achieved the same results with any variation of thinned epoxy.... period.

CPES was developed and sold for the advertised purposes. Since epoxy is part of it's name, all one can assume is that it is a very low viscosity epoxy. It seems many are willing to make all kinds of assumptions as to what it is and how easy it is to reproduce its capabilities with "thinned epoxy". This is illogical from the get go... IMHO.

I'm curious as to whether any of those who are skeptical about the value of CPES: 1) have used it 2) read the studies done to evaluate its ability to penetrate wood, it's effectiveness as a sealer and moisture barrier. 3) Have tried thinned epoxy and CPES simultaneously for the same purpose and compared the results, etc, etc.

In reality, I only use CPES for some specific situations where it's features are taken advantage of and it is an ideal product for such use.

Note: If John wants to seal his boat and paint it... its hard to beat CPES (especially if you are determined to avoid coating the material with normal epoxy). Application of CPES is easy and provides a tenacious bond with the paint. My $180 two gallon kit has lasted more than 3 years... its a no brainer.


RodB

http://www.woodrestoration.com/

http://www.woodrestoration.com/woodrestoration04.pdf

page 8.6

8.6 Product description from the manufacturer
The Professional Version of Clear Penetrating Epoxy Sealer is designed to dissolve not only the saps and oils in the wood but also the natural water, and to keep the impregnating resin dissolved ("in solution") in the presence of those saps, oils and moisture of the wood. This permits the solvent-resin mix to efficiently penetrate the natural porosity of the wood. Fungi and bacteria produce an additional porosity that is especially penetrable by this product.
The resin system is formulated primarily with resins derived from wood and therefore the resin system is compatible with the chemistry of wood in a way that no other resin system is. The resin system is very hydrophobic to inhibit liquid water accumulation in impregnated regions while allowing (via the designed porosity remaining in the wood) the diffusion of water vapor through the impregnated region as well as the natural porosity of the wood. Wood impregnated with this system has a toughness and flexibility comparable to the original wood, because the resin system itself has a toughness and a flexibility comparable to the original wood.
When fungi and bacteria eat their way into wood, they destroy the material and create porosity on a gradient between the sound wood, the slightly porous wood with fungal spores in that region but the wood apparently sound, and then more obviously deteriorated wood, until at the extreme there is wood so porous and so obviously deteriorated you could stick your finger into it.
When wood is impregnated with this material, the penetration extends all the way through the zone of deteriorated wood containing bacterial and fungal spores, and on into any available porosity of the sound wood. This impregnation helps the wood resist further deterioration such as might be caused by fungi or bacteria.
Because the primary purpose of the product is not to kill fungi or bacteria or encapsulate fungal spores in epoxy, thus possibly stopping them from hatching, (even though it might do that) the Federal EPA and the California EPA (Environmental Protection Agency) do not allow such claims to be made unless the product is registered as a pesticide. Since the primary purpose of the product is the mechanical restoration of deteriorated wood, the
product is not registered as a pesticide. Consequently no such claims are made by the manufacturer and others are discouraged from making such claims.
The sole claim for this product is that it can improve the physical properties of wood in some circumstances, and that it can help the wood resist further deterioration such as might be caused by fungi, bacteria, etc. Contributing to this claim is the fact that varnish, oil-base enamel paint and most latex paints stick better and last longer when applied to wood that has been treated first with Smith & Co. Clear Penetrating Epoxy Sealer. This has been a consistent observation by thousands of Smith & Co. customers, since 1972. Improving coating adhesion directly helps the wood resist decay.
The Professional Version of Clear Penetrating Epoxy Sealer and a compatible family of fillers are used by factory-trained technicians under the registered trademark LIGNU® to effect restoration of architectural structures. This trademark is owned by Steve Smith.

Penetration tests....
http://www.rotdoctor.com/test/penetration.html