The Rot Doctor


Subject: rot (and CPES)
Date: Thu, 02 Aug 2001

I have used CPES on some spots. I am now told by a wood boat expert who helped restore the Pride of Baltimore that borate(?) is the only thing that will prevent rot, and if I use epoxy it will prevent swelling. I really want to prevent future rot, should I apply a single thin coat to do this? I am confused. Dave

The borates will prevent rot, but only for "X" period of time. The borate crystals are gradually leached away by moisture and the application should be re-done at periodic intervals. Borates restore no structural strength to wood.

The business of epoxy and wood swelling, or "breathing", gets confused because a standard epoxy resin, a thick resin, will prevent the wood from breathing. CPES is different. It is epoxy, but is diluted by a solvent mix (14 different solvents) and so is carried into the wood, rather than laying on the surface. Wood that has been treated with one coat of CPES will still breathe, although the "breathability" is reduced by about 50%. This means that the wood will swell, but just at a slower rate. Additional coats of the CPES will gradually close off the surface of the wood and prevent breathing, and therefore swelling.

There are custom boat builders who will apply one coat of CPES to all new wood going into the boat.

When CPES is used in local areas to treat and solidify wood, the breathability issue becomes less important. What one is after here is to restore that one local area. The wood surrounding it will breathe/swell as normal, and generally speaking just carry the treated area along with it. One side of a piece of wood coated with CPES can reduce breathing, while the other side allows breathing as normal.

Hope this has been helpful. Come back if you have additional questions.