The Rot Doctor


Subject: CPES good for any kind of wood?
Date: Wed, 18 May 2005

Dr Rot,

I've used CPES for a couple of years now, mostly on plywood, which soaks it up like a sponge. But now I'm replacing some trim boards on a big garage door, long narrow 1" X 1/4" X 8' pieces of "whitewood". Even after letting the ends sit in CPES for a couple of minutes, they don't seem to absorb much, neither do the sides when I brush it on. So now I'm guessing harder woods aren't as treatable with CPES, and they won't be sealed as effectively? Should I just be using a regular primer for them?

Even on new wood, CPES is absorbed to some extent and sets up an epoxy barrier. We believe this absorption is particularly important on cut ends. The end-grain may not seem to absorb much, but it absorbs enough to set up that important epoxy barrier.

As a general statement I would say that CPES on the ends of new wood is an important deterrent to rot and deterioration, and its use on the flat surfaces would be optional. If the paint is applied within 24-48 hours of the CPES then a particularly good bond is achieved, and this can be either a primer paint, or the final coating.

On structures such as garage doors, windows, etc., the use of CPES at any point where one piece of wood joins another is important. This is where moisture can becomes trapped and trapped moisture greatly increases the chances of rot developing.