The Rot Doctor


Subject: Re: log home question
Date: Fri, 29 Jan 1999

Dear Doc

You've answered my question on using your products on new wood well. I'll talk to the homeowners and the contractor. I have a follow-up question. They have asked me to seal some checks that lead into the house, the sort that allow bugs and air and water to get in. I read a response your wrote to some log home forum question suggesting soaking the check with one of your products (I assume the same CPES you suggested for use on new wood) before sealing.

That is correct. It's CPES.

I have sealed checks before using good caulking, though I've always warned the customer that if the seal is broken on the caulking then water could get in behind it and cause hidden rot. Your product, applied properly, would seem to minimize this threat. Will caulking (I usually use high quality acrylic-latex caulks) adhere well to wood after CPES has been applied to it?

All caulking materials, including the acrylic-latex, will stick just fine to CPES-treated wood. Do allow 2-3 days for the CPES carrier-solvents to vent away before applying the caulk. The epoxy itself will cure underneath the caulk.

It sounds like your products are ones that I will be using and advising others to use. I suspect I will have a lot of questions over the next few weeks while I think of the various situations where epoxy might solve the problem. Hope my inquiries aren't too much trouble.

The very nature of a direct-sales Internet business is communications with our customers. We are happy to answer any questions in advance, and are happy to give opinions and advice on projects as they are being completed. We check e-mail often every day during the week, and at least once a day over weekends. Feel free to call at any time if the question is too complicated to outline on e-mail.

I know this is probably a question with so many variables that it cannot be answered, but do you have any guidelines as to how much CPES is required to seal pine logs. I assume that I am probably going to have to just buy a few gallons and see how far it goes, but I thought I'd ask.

It's a good question. Much depends on the absorbency of the wood. One always wants to apply as much CPES as the wood will absorb, remembering that in applications into deep or rotted wood that it can take as long as several weeks for the carrier solvents to evaporate away. The rule of thumb is to give the area a sniff and if there is a strong solvent odor then more venting time is required.

Anyway, back to coverage...on good, bare wood you can figure on about 200-300 sq feet per gallon. CPES is good for bare wood, but it's not something we recommend strongly because of the cost to the homeowner. Also, as noted below, CPES-coated wood does not accept stains and finished well. When applied to cracks and crevices, you should apply as much CPES as the wood will absorb. On the end of logs the end-grain, especially if dry, will sometimes absorb surprising amounts. This is good. Wood that has been soaked in CPES will be highly rot resistant.

So, you're basically right when you say that you'll just have to buy a few gallons and see how far it goes. We have CPES always in stock and ship the same day as ordered if the order is in before 2pm Pacific time.

Another question. I assume that stains don't adhere to wood surfaces that have been treated with the epoxies. When it is time to refinish the house (annually if they keep using the stuff they have on it now) what does it take to match the epoxy saturated end-grain, for instance, with the non-epoxied surfaces. Also, the finish they are using now, as is usual with oil-based stains, looses its sheen rather rapidly, something I assume epoxy does not do. Do you know of any solutions for that problem.

When CPES and stains are used together the stain must be a water-based stain and go on the wood first. After it has dried then CPES can be applied over the stain and effectively locks it in. Usually 2 coats of CPES are used. This really isn't too practical a solution for log homes, so what we recommend is that just the cracks and crevices be treated INSIDE, and the final stain-finish applied. In this case it can be oil-based -- it will just sit on the CPES inside the wood. Overall appearance won't really be affected. Oil-based stains lose their effectiveness in about a year, and the petroleum part of the stain oxidizes away, so CPES can be re-applied -- if necessary.

Wood rarely starts to rot on an open surface. As you have observed, it is the moisture that is trapped behind caulking, in cracks and end-grain that causes the problems. So you are quite right to be concerned about the wood adjoining the caulking.

End-grain applications of CPES are not so great a problem, because so much of the CPES goes deep into the wood. We suggest that you do a little test somewhere, applying the CPES and then going back with the stain to see what the visual effect is. CPES can be tinted with resin-dyes, which come in all colors (including brown) and are available at Marine-supply houses. West Marine sells them for a few bucks a tube. Again, tint some up if you want and do a little test somewhere.

After typing the word epoxy a dozen times or so I'm learning where the x is on my keyboard.

Thank you for your help. I'll be discussing the use of CPES on the exposed deck with the contractor on Monday, so I assume I will be talking to you again soon.

Thank You

Bob H.


Yeah, we REALLY know where the x is! Feel free to come back with questions. If CPES is used judiciously in just the right applications is does help protect the wood and is not horribly expensive for the homeowner. It does save a LOT of money down the road. Replacing rotten wood is time consuming and can get very expensive.