CPES and thinned epoxy

[Island_Tom]

In my readings I ran across the following link from WEST Systems.

Thought it might be of interest to some.

Tom

http://www.boatbuilding.net/article.pl?sid=05/12/30/1439227&mode=thread

[Ian McColgin]

While I started my infatuation with epoxy earlier, it's only since 1974 that I've been using it with consistant wit and understanding. I sure remember the days before reliable propriatary epoxy formulations.

I believe that with epoxies, those of us who are not chemists are better off understanding a small number of propriatary products well, rather than making up theories of this product for that temperature or moisture content or woor or whatever.

I use WEST for bonding, Gluvit for large area to be painted later coating, and CPES for new wood sealing. I am not an epoxy chemist. Here are my observations.

The googebros essay is spot on about the relative merits of penetration for their product. In fact, some of us have been fans of the stuff back when the 'S' stood for 'Saturation.' The googebros changed their tune as they learned, quite correctly.

I much liked their unstated side swipes at RotDoctor type propaganda. Epoxy saturated rotten cellulous is just that, as many of us learned at silly expense.

However, CPES is not simply thinned epoxy and it behaves differently from thinned WEST. WEST (I'd not thin it) can be used as a primer/sealer. For a surface primer/sealer, I think Gluvit works better.

But CPES really does prime and seal best of all if your goal is also wood preservation and if you have a fairly clean surface that you're not trying to fill and level. Maybe it's that CPES's volitiles don't only evaporate off the surface. Whatever happens, CPES spreads it's essence quite deeply into the wood.

I had occasion to help install some new keel bolts in a Wianno keel that had been CPES'd about five years earlier. We could detect CPES in the bore shavings a good four inches from the CPES'd surface. No wonder stuff that's been CPES'd does not rot. That's not just thinned epoxy. That's a different material in some way.

Anyway, the googe bros, Mr Smith, and other boat oriented epoxy formulators have done wonders at making our access to and understanding of their products really quite wonderful.

[FSS172]

Also in the 'might be of interest' category - After searching for this information in the other threads on CPES and not finding it, I just picked up the MSDS for Smith's CPES. Here are the hazardous ingredients listed.

Unspecified Aromatic Hydrocarbon - identified as Naptha
by it's CAS number via Chemfinder
Xylene
Toluene
Isopropyl Alcohol
2-Butanone - aka Methyl Ethyl Ketone
4-Methyl 2-Pentanone
2-Heptanone
4-Methyl 2-Hexanone
2-Pentanone
Dipropylene Glycol Monomethylether
Diisobutyl Ketone
Ethyl Acetate
Isobutyl Acetate
Ethyl 3-Ethoxy Proprionate
Propylene Glycol Monomethylether Acetate
Hexyl Acetate
Isobutyl Isobutyrate
Diacetone Alcohol
Cyclohexanone

These are only the 'hazardous' ingredients and don't seem to include the resin components themselves; but presumably, this list covers most if not all of the solvents. There's no info on an MSDS about the percentage of each; does anyone know if they're listed in descending order of percentage like on food products. Googling each these ingredients makes for interesting reading... Anyhow, it's clear why the stuff smells so good
tongue.gif

[emichaels]

[ 01-05-2006, 08:33 AM: Message edited by: emichaels ]

[Dave Carnell]

Note that epoxy resin is not included in the list of components. Queried some years ago as to why this is so, the reply was that there is too little epoxy to be listed. They feature penetration tests on dry balsa wood. The first drop of water you add to mixed CPES starts to precipitate solid, illustrating that there will be very little penetration of CPES into wet wood.

Kill the rot with ethylene glycol antifreeze. Then if you want to consolidate the rotted wood, dry it out and use epoxy resin diluted with a minimum of solvent.

[kulas44]

most automotive antifreeze has silicone in it. Long after the alcohol is gone the silicone is still there. If you have ever scraped off silicone sealant, then cleaned and prepped the area the best you can, then painted it, you would know that paint don't like silly cone.

[Don Kurylko]

Greetings Dave,

Would Propylene Glycol based anti-freeze (the non-toxic to animals alternative) be as effective as Ethylene Glycol? Been meaning to ask you that question for ages.

Don

[Ian McColgin]

What's with the antifreeze kick. We are cromudgeounly here and like to have strange solutions to common and easily solved problems, but really, antifreeze is only good as antifreeze. It's not an effective way to treat wood.

Even with real wood preservatives it's well on to useless to apply treatments after the boat is built. People still buy Cuprinol and splash the bilges, but I have doubts as to what it gets them and it's only safe in an open boat anyway.

There are some commercial wood treatments that actually work but most are also toxic to humans and many degrade glue performance, if that matters in your construction.

If you have a cruising boat, the consequences of wood treatments poisoning the interior atmosphere is to be considered.

Traditional construction and good upkeep to prevent fresh water or damp accumulation and maybe a little rock salt atop the butt blocks work fine.

CPES travels so far it is an effective, if a bit costly, rot and worm barrior. The fumes are toxic but once properly cured there is no known environmental problem to a boat's interior.

There are some hulls that appear designed to rot, with lots of impossible to vent space.

G'luck

[Tom Robb]

Some time ago this subject was beat to death.
Why resurect it? :(

[emichaels]

FWIW.

I remember something in Pardey's book about leaving the frame ends long and boring a 1" diameter hole an inch or so deep on top, pour in a toxic wood perservative and, I forget how much time passes, not much, and it comes out the other end fully coating the inner wood of the frame for the whole length.

Eric

[RodB]

I turned a gunsmith friend of mine onto CPES for resurrecting an old wooden lightning. He ended up scraping the Lightning but still had the CPES. He has found it the number one best sealer for rifle stocks that he has ever used bar none. I can get more details, but he just doesn't stop raving about CPES and how it protects quality walnut stocks.

I too wonder why many are so negatively disposed towards CPES, but it seems to me that if one reads up on its use, it is certainly not thinned epoxy. One good conversation with Mr Smith and you'll be convinced to give it a try, even though it is so damn expensive.

RB

[Thorne]

Remember there is also various types of CPES -- I'm currently using Smith's Cold Weather forumla and it is GREAT.

It cures much more rapidly, and makes a great base-coat for either paint or varnish - Smith recommends it even in relatively warm weather for indoor (or in-boat) applications due to the rapid cure. You still need a respirator, of course!

So, we not only have differences between various brands of epoxies and CPES, but also some variation within brands. Interesting to see how it builds up on the surface of white oak like varnish...

[Bob Cleek]

I'll second everything Ian has said about this subject. As for the expense of CPES, I haven't found it any more expensive than any other epoxy-type formulations. A little bit of CPES goes a LONG way. The "savings" are in reduced maintenance, since whatever it is under will last a much longer time. BTW, I'll bet Steve Smith would love to hear about CPES being embraced by the gunsmiths! He doesn't go looking for new applications, I don't think. I've never seen CPES advertised at all, though maybe it is somewhere. The amount consumed based on word of mouth is really amazing. Try it, you'll like it! And, "No, Virginia, it isn't just thinned epoxy!"

[pipefitter]

I once had some minor epoxy chores to do and only had one chip brush left. I soaked it in denatured alcohol and smashed the excess epoxy out of it and was able to use it for a few batches that day. When I was finished,I dumped the container in which I had cleaned the brush onto a scrap piece of plywood and never gave it another thought. The other day when I picked up the scrap from outside,the place where I had dumped the alcohol was still alot like new and has a crystaline appearance to it and the wood fibres are sealed.Not like the plastic like coating from unthinned epoxy but like surface to subsurface. The percentage ratio of epoxy to alcohol had to be quite low as it was still very thin like straight alcohol when I dumped it.Now maybe it is more porous than unthinned epoxy but would this still not make a decent primer for subsequent coats of the unthinned epoxy? Like an epoxy based sanding sealer or something? Also,a paint stick stood on end in the same solution wicked up a decent amount above the liquid line and it is also sealed somewhat beyond that point.

[ 01-06-2006, 02:35 AM: Message edited by: pipefitter ]

[RodB]

Bob,
I have the two gallon pk of CPES and have used it several times over the past 3 years. I only paid about $100 including shipping but my gunsmith friend paid almost $150 for the same amount about a year ago (including shipping). ..thats damn expensive but I will buy and use it anyway.

I will have my gunsmith friend (he builds custom rifles) detail his use of CPES on stocks. He has stated he has never seen a better sealer... that also allows application of other products afterwards. I think he has experimented quite a bit.

RB

[Dave Carnell]

Antifreeze formulations may have some silicates, but no silicones. Antifreeze-treated wood takes all finishes and glues, including epoxy.

The worst snake oil hype of Smith is the claim that their products have properties like wood because they are derived from wood. They do not make epoxy resins and the ones they use are petrochemical products. Some of their solvents could be made from wood, but their properties would be identical to the same solvents synthesized from petroleum. For example, methanol was called wood alcohol in the 1920s because it was produced by destructive distillation of wood. Today it is all made from natural gas, but its properties are the same. Methanol is methanol and nothing else.

[Bob Cleek]

I don't know that I've ever heard or read that Smith's products "are made from wood." I've spoken personally with Steve Smith about many of his products over the years. He is a chemist and his comments on his products have always been what you would expect from a scientist, not a salesman. Smith's operation is primarily an industrial coatings business. I believe that marine applications for his products were secondary to their original intended uses. (CPES was originally developed as a sealer for architectural applications, I believe.) On the other hand, I have myself fumed over the outrageous claims OTHERS (e.g. "Rot Doctor") have made for Smith's products (CPES) which they sell repackaged under their own label. As with any product of this nature, it is not a cure-all. They are only good for the uses intended, or developed over time.

[peter osberg]

I too have been lead down the garden path of epoxy claims and would suggest anyone who relies on epoxy +- some thinned penetration, do a simple creep and stress test before 'doing a sound sleep test' on a routine and product. What I found illuminating was to do a 10-1 scarf of two 10 ft pieces of ash them hang a wieght from one end after the bond had cured for a week. After days/weeks, I found considerable differences between product lines in terms of creep as well as surface bonding affects.
peter

[Keith Wilson]

An EXCELLENT point from the linked article, and one that bears repeating:


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 1/4" into the wood or 5/1000". 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.
I'd be very interested in a similar test of wood treated using Robb White's technique of applying epoxy to hot wood (as hot as possible, short of burning down the shop), then cooling it to draw the epoxy into the wood strucure. I've used a similar procedure with linseed oil on small parts - heating the wood in the oven, then immersing in linseed oil until it's cold, and verified penetration of over 1.5" from any surface into oak. I was very surprised.

[ 01-06-2006, 03:44 PM: Message edited by: Keith Wilson ]

[pipefitter]

But it also seems that failures in epoxied joints that occur over time was when water made it's way between the epoxy and the wood such as on glass and epoxy over wood delaminations. Would deeper penetration of the epoxy prolong the life of the joint or glue barrier? Thats what I thought the reasoning of penetrating epoxy formulations was hoping to accomplish.To extend that barrier.I still doubt it would be a major factor on dry sailed,well maintained boats.

When I asked a boatbuilder I know that built with polyester over wood about adding thinners to resin he still claimed I would do more repair fixing gouges and damage from use more than would be repairing blisters or delams or rot caused from voids in plywood.He also warned me to drill holes for woodscrews slightly short as to not leave voids beyond the points of the screws.

Also to add...I was told that a heat gun set on low fan would thin resin and remove air bubbles.

[ 01-06-2006, 09:51 PM: Message edited by: pipefitter ]

[Bob Cleek]

Keith, that section you pasted is a bit misleading for our purposes. When they talk about no greater adhesion with epoxy penetration in all but hardwoods, what they are really saying, I think, is that in most woods, the GLUE JOINT ADHESION fails at the wood/adhesive interfacce, which could easily be that point at which the penetrating epoxy stopped. I can't speak to the molecular bonding that occurs between CPES and a subsequent layer of epoxy, but the scientists claim this happens. I do know that the penetration of CPES is wonderful for stabilizing the surface for paint or varnish and makes wood apparently impervious to marine borers. (Jury's still out on that one, but I've yet to hear of anybody having worm or gribble problems after CPESing their bottom.)

[Keith Wilson]

Bob, sorry to be confusing. The section I pasted is about structural adhesives; it has nothing to do with epoxy as a primer under paint and varnish. That's a different application altogether, and one at which CPES excels. I always use CPES under paint and varnish, and it seems to extend the coating life very significantly.

[Dave Carnell]

Propylene glycol will not kill rot organisms because it is non-toxic. Ethylene gkycol antifreeze contains about 10% diethylene glycol of equal toxicity. Antifreeze also kills wood-boring insects.

"The particular resins used in Smith & Co. products are substantially derived from wood itself because these particular resins, when they cure, will have a toughness and flexibility that is comparable to the originaly wood." Copyright 1996 Steve Smith.

[RodB]

This is a simple thing, but when I have used both CPES and thinned epoxy (using acetone and once Naptha) I
just noticed the difference as to how it soaks in and what you seem to have as an end results. The CPES is just so homogenous and whatever properties it has, it carries them into the wood soaking in untill it reaches a point where no more will go in.

Mostly I just used thinned epoxy to saturate/lock down the ground walnuts shells on my non-skid, which was only a test. When thinning epoxy I subjectively felt the properties of the epoxy were negatively affected from looking at the residue once dried both in my container and on the wood.

BTW, I later just decided to use the paint to lock down said non-skid particles for several reasons.

CPES on the other hand just is sucked up into the wood until you get to the point that it will not soak in any more. Initial applications just soak in completely...and are gone.

As to what its doing and how it works over time, I can
only go from the wood restoration site project and of course Smith and co and the other materials you can find on folks experiences with it.

Some may be right, in that is is just a thinned epoxy mixture, but it sure works under paint to protect the wood better than paint alone... Tests have shown that and I doubt that thinned epoxy in a heads up test would have the same results.... see the following.

One very bad experience to relate... where
thinned epoxy was used in a new boat construction. A boatbuilder in South Texas built one of Reuel Parker's larger boats and when the hull was done, he applied thinned epoxy to the interior of the hull until no more would soak
in (inner layer doug fir tongue and groove) ...then he primed and painted with linear
polyurathane.

Anyways, a few years go by and he lets the project sit almost at completion. Now the hull was not tarped very well so water got in now and then when it rained hard, and of course coastal Texas had plenty of humidity and
heat.

So, what happened was after sitting up for a few years (at least 5-7 yrs) moisture/rot worked its way into ice compartment via the hatch in the cockpit seat....down into the cockpit floor and most supporting buikheads in the aft center of the hull...then from
the ice box that was constructed under the port lazzarrette seat running into
the galley where one had access to the ice from the galley. The moisture/rot then moved down the under structure of the ice box to the cabin sole which was really the inner layer of the hull (5/8" Doug fir tongue and groove) covering about 6-8 square feet near the foot of the companionway ladder extending towards the centerboard trunk but mostly to the starboard floor area. Note: only exterior surfaces of ply panels in cockpit were glassed, all the rest was coated with epoxy and painted.

All described had to be removed including the bulkhead under the cabin
entryway, the large section of the 5/8" tongue and groove inner hull layer, the ice box and of course the entire cockpit flooring and attached supporting bulkheads.

Bottom line, the thinned
epoxy soaking in conjuction with linear polyurathane paint did not protect the interior layer of the hull in these conditions and
the boat was a mess. A real nightmare, but one must realize that no matter what the construction methodology, these conditions of intermittent influx of water with lots of heat and humidity are a formula for rot period... in any boat for that many years.

BTW, the interior layer of the hull which was
doug fir tongue and groove edged glued with epoxy and
of course sealed with thinned epoxy and painted with LP as described was a real NIGHTMARE TO REPAIR. Another note: the plywood in the cockpit and
boat interior construction was good exterior grade construction stuff, NOT MARINE PLY, and only exterior ply panels in the cockpit etc were glassed on their outward surfaces.

The conditions of this hull were the most extreme test
any boat construction/materials system could have undergone, and I'll bet even if the interior of the hull had been glassed, the conditions would have
also allowed moisture to get under the glass to the wood and still cause rot in the interior layer of the hull? . Obviously a mitigating factor is the plywood in the cockpit flooring and nearby bulkheads not being marine grade, just exterior grade construciton stuff, which is probably a contributing factor to the seriousness and extent of the rot. Epoxy is not superman...

I have always wondered if he had used CPES instead of thinned epoxy on the interior hull layer...would the rather large section of rot at
the cabin entry in the hull be less or even avoided?...ie., with CPES and LP paint between the water and the tongue and groove layer. I guess even CPES has its limits and glassing the interiro layer would have been much better.

He would have probably used plenty of CPES to coat
the interior of the hull though...which is a great argument for encapsulation with regular epoxy.

I see glassing the interior of the hull and perhaps certain
plywood panels (those with their bottom in risky areas for getting exposed to water) as the number one ultimate method in giving the boat longevity...but if the
boat had been maintained properly and reasonably protected, then she would
probably have been fine. I would want to be sure to do a real good job encapsulating the interior structural bulkheads though and of course always keep water from getting into the boat along with maintaining good ventilation.

Note: a simple piece of furniture in pine will last
many many years just sitting in a garage out of the
rain and sun...with virtually no protective products applied.
...its all about maintenance and care.

If I was painting wood, whether
exterior and interior... I wouldn't even bat an eye about using CPES first on all surfaces before priming and painting...thats my story and I'm sticking to it.

RB

[ 01-07-2006, 01:42 PM: Message edited by: RodB ]

[Bob Cleek]

Looks like you were right, Dave... sort of. I suppose some of those solvents that penetrate wood are derived from wood and are closer to the modulus of elasticity, or whatever. I still don't think that equates to "strong as wood because it's made of wood." Again, I think CPES is great stuff as long as it's used for what was intended, a sealer beneath a standard coating. All the CPES in the world isn't ever going to turn a wooden boat into an impermeable epoxy boat and wasn't intended to do so.

[pipefitter]

Even if CPES was a miracle cure I still wouldn't trust it beyond what I would paint alone. I would still maintain my boat as if it had nothing on it at all.I think these products tend to give builders and repair people false confidence and to make bad design choices. Like inaccessible bilge areas or places where water can be trapped.I still think we would all be better off if we just treated these products as adhesives and minimal primers and face the facts that we may have to check and redo these areas of our boats from time to time.One reason I am not an advocate of foam filled decks on any boat containing wood,glassed or not.

[carioca1232001]

Dave Carnell wrote:


Propylene glycol will not kill rot organisms because it is non-toxic. Ethylene gkycol antifreeze contains about 10% diethylene glycol of equal toxicity. Antifreeze also kills wood-boring insects.
I was tempted to look into your homepage on Thursday evening on seeing this issue being brought up again on the WBF. ;)

So I got myself a litre of ethylene glycol and 1kg each of borax and boric acid, mixed them together in the right proportion of 50:28:22 (by weight), brought the brew to a boil (125ºC) when it became clear (transparent) again, let it cool down and applied it yesterday evening over some affected wood around the perimeter (horizontal structural members) of the aft deck.

Hopefully, I will have wiped out the blighters forever ! :D

The structural wood is still basically sound (acceptable) but to ignore the superficial fungus attack would inevitably have lead to total degradation some years down the road.

Water got trapped between the planking on the aft deck perimeter and the underlying structure. The new planking to be installed this coming week will see to it that this possibility be eliminated altogether (Sikaflex or preferably, some other bedding material)

Thanks for sharing your valuable experience and database ! smile.gif