Experienced Epoxy users... CPES?

[cuyeda]

A recent thread about different brands of epoxy brought up a burning question about CPES. Recently, I mixed up a batch of the West System epoxy resin, and diluted it with mineral spirits. Thus, making a batch of my own version of the CPES product by Rot Doctor. The consistency was not as thin as the CPES, and penetrated well for my application. CPES is not inexpensive, and seems to disappear as quickly when applying it. Several coats until saturated could eventually use up the expensive supply of CPES in a blink of an eye.

My question: Is the CPES product superior for the intended use, vs. mixing your own, as I have done?
I have used the CPES product once. Many people have stated using CPES while building. It just seems easier to have one product than to special order CPES directly from Rot Doctor. I could purchase epoxy within driving distance, and not have to pay the extra shipping for CPES.

[angib]

I'll throw in my heretical view: any solvent in epoxy is a bad idea if it is for protecting good wood. Your aim should be to create an epoxy-rich layer that will be as nearly waterproof as possible. If there is a solvent in it, it will leave voids when it evaporates, creating a less waterproof layer, offering less protection to the wood.

If the use of the epoxy is to reinforce rotted or softened wood, which I understand was the purpose of CPES, then solvents may be a good idea - I've no experience of that so I don't have an opinion.

Epoxy is not paint, and however much anyone reveres their grandfather's instruction to get a coating to soak a long way into wood, the mechanics are different. Soaking epoxy into end-grain, for example, is primarily a one-shot deal - you must continually feed the same mix of epoxy into the end grain until it stops being absorbed. Typically, this means applying epoxy to the end grain maybe six times in ten minutes and only stopping when the epoxy starts to harden.

[madjack]

I'll throw in my heretical view: any solvent in epoxy is a bad idea if it is for protecting good wood. Your aim should be to create an epoxy-rich layer that will be as nearly waterproof as possible. If there is a solvent in it, it will leave voids when it evaporates, creating a less waterproof layer, offering less protection to the wood.

If the use of the epoxy is to reinforce rotted or softened wood, which I understand was the purpose of CPES, then solvents may be a good idea - I've no experience of that so I don't have an opinion.

Epoxy is not paint, and however much anyone reveres their grandfather's instruction to get a coating to soak a long way into wood, the mechanics are different. Soaking epoxy into end-grain, for example, is primarily a one-shot deal - you must continually feed the same mix of epoxy into the end grain until it stops being absorbed. Typically, this means applying epoxy to the end grain maybe six times in ten minutes and only stopping when the epoxy starts to harden.

+1+ CPES is best used for it's intended purpose...INJECTING into rotted or damaged wood...your experience and mileage may vary................
madjack

[S. Heisley]

In all fairness to the inventor of CPES, Steve Smith, perhaps you should read what he suggests; thus, hearing from the "other side":

Hello. I'm Steve Smith. I'm the guy who invented Clear Penetrating Epoxy Sealer [also known as CPES], back in 1972. I've gathered up and organized quite a bit of information about it, since then.

I originally invented it as a solution to slightly deteriorated wood. It turned out it also was (I modestly assert) the World's Greatest Primer for paint or varnish on wood.

It is distributed by Smith & Co. under two names, CPES (above) and MultiWoodPrime. The MultiWoodPrime website http://www.multiwoodprime.com/ has information about its benefits on new or sound wood. There is information at the main company website http://www.smithandcompany.org/ about the product and its use in the restoration of wood. One of my distributors is The Rot Doctor, who serves the general public with Internet sales.

The underlying science of how it works is given at http://www.woodrestoration.com/. There you can see time-lapse photographs,pictures thru microscopes, mechanical tests and even an open standard for this kind of product.

The information at those websites should answer a lot of your questions. If it makes new ones, just ask.

Steve Smith

The above was quoted from:

http://tnttt.com/viewto ... teve+smith

Steve became a member here so he could comment on his product to all of us; and, from that redirect, you can look up all his comments and see everything he has to say. Hopefully, this will keep the level bubble in the middle for you so that you can choose what is best for you.

If you do decide to go with the cheaper product, I don't think I would dilute it as that is not going to do the same thing as CPES and it isn't going to do the cheaper product justice, either.

[madjack]

...true story...when I went to use my tear this year after it had sat up all of last, I found a leak and subsequent rot problem...the ply in question had been coated with RAKA non-blushing epoxy on the outside and the edges...the rot was in the uncoated portions on the inside of the galley...when I removed the rotted wood, I found a solid 1/8" area on both the sides and edges that was totally unaffected by the rot...this was with just the "regular" epoxy...seemed like pretty good penetration to me...I do not know what that are would have been like with CPES but I was happy with the performance of the RAKA product.............
madjack

[S. Heisley]

It has been said that the main reason for failure in epoxy applications stems from the person applying the product and not the product itself. No product has a warranty for that.

[madjack]

...the failure was not from the epoxy but rather the seal...or possibly a nut problem...the nut that the chose and applied the seal failed
madjack

[doug hodder]

I would bet that there have been a higher number of sealing failures on this forum from the use of CPES than regular epoxy. Just based on what I've read from others experiences. Doug

[S. Heisley]

You can't just slap a coat of any epoxy on and think its good enough. You have to pay attention to what you are doing, not miss any spots, and follow instructions properly, including mixing it properly, in the proper ratio amounts. (That comment is not directed at you, Cuyeda or MJ or Doug.... You all definitely know what you are doing.) Unfortunately, we are all human and prone to slip-ups from time to time:

With most epoxies, if you mix it incorrectly, you'll either have a product that is too thick or too runny or sets up too fast, etc; so, you'll know you did it wrong. With CPES, there is very little tell-tale thickness or thinness to go by, so, you just have to pay attention to your mixing ratio from the start.

Also, the key to applying CPES is to apply it until no more will absorb. That's where most people fail. It's different from the other epoxies. We're sort of talking apples and oranges. Both are "fruit" and will probably satisfy your need. They just do it differently.

[S. Heisley]

But, back to your original question. I think MadJack stated it very well here:

...the rot was in the uncoated portions on the inside of the galley...when I removed the rotted wood, I found a solid 1/8" area on both the sides and edges that was totally unaffected by the rot...this was with just the "regular" epoxy...

Therein lies the difference. Most epoxies are meant to be a coating that shields the wood. Thinning out the epoxy is probably just going to give you a thinner coating and not necessarily be absorbed by the wood.

If you still want to thin your epoxy, I would perform a few experiments. First, I would color the thinned epoxy so that when you apply it to a test piece of wood, you can cut through the wood and see how far it is absorbed. Also, you'll want to completely coat a piece of wood and then allow it to soak in water and sit in the sun...and soak in water and sit in the sun...and soak in water and sit in the sun..... (I think you get the drift of my meaning.) Anything less than the test of elements and time will not tell you what you want to know. Do you really want to walk an unchartered trail and put all your hard work possibly in jeopardy?

[cuyeda]

Thanks for the replies! Such a wealth of wisdom! My only experience of mixing was applied to a 2" laminated ply creating a frame for my TTT. Because it was end grain plywood it did absorb rather nicely. In this case I think it would be fine. The result was a stronger framework, and water damage deterent.

However, after reading some of the comments, I thought to myself that a plywood surface may have different results in absorption. Applying a water deterent to roof and wall skins of trailer I may just skip the CPES, and go with an epoxy coating.

Thanks for letting me bounce this around.

[2bits]

Personally I think CPES and "regular" Epoxy are for different uses. CPES is for Penetrating end grain and not coating the exterior, while Standard Epoxy is for coating/sealing, but not so much for penetrating. CPES can be used for sealing too, but due to the thinner nature of the product, it will take many more coats, which may be why people put 2-3 coats of CPES on and experience failure. Just my thoughts from my own experience. I love the CPES stuff for endgrain. I like that it disappears into the end grain and begs for reapplication, because to me that means it is doing what it was designed to do, soak deeeeep into the wood. It is definitely most effective on endgrain.

[Steve_Cox]

Another two cents - Andrew mentioned this a long time ago and it's something I subscribe to, when sealing end grain plywood with epoxy use as a minimum 3 coats and fill the endgrain until it is smooth. That will ensure encapsulation of the wood fibers when added to a couple of coats of epoxy on the faces of the plywood as well.

[2bits]

Yup, Now that I have had my baptism into failure, I drop three coats of CPES into the end grain and then cap it off the the rot docs EZ Fillit. I used Helmsman SPAR Urethane for the faces... three coats but recommend 5.

[cuyeda]

It's becoming clearer to me now...