The Rot Doctor


Subject: CPES and borates
Date: Fri, 27 Oct 2000

You mention in some areas on your site that borates can be useful after CPES treatments as well as borates leaching via moisture. I don't understand the logic. Doesn't the CPES essentially encase the wood fibers and stop them from transmitting water? If so, why wouldn't you apply the borates and then CPES to seal in the borates? Also, how would the borates be effective on CPES treatment if the treatment seals the fibers?



Not everyone wants to spend the dollars to treat all the wood with CPES. In a home attic, for example, CPES may be applied to specific deteriorated areas, but the homeowner may elect to spray the entire wood structure of the attic with borates to discourage rot. Same with a boat hull -- treat the rot in a specific area and then spray the hull interior to discourage future rot.

Your logic is correct in that if CPES is applied then the borates are unnecessary, for the very reason you mention. You CAN apply a water-borne borate solution, wait for the wood to dry, and then apply the CPES, but we don't see the point. Once the CPES is in/on the wood then the borates are not necessary, as you note. And the CPES treatment is a permanent, one-time application. Borates do nothing to reconstitute soft wood and they are gradually leached away by moisture.

There are some borate-products available that have the borate mixed in with glycols, with the idea that the glycol will hold the borates in the wood for a longer period of time. Our testing shows that glycols impede the penetration of CPES so we do not recommend that they be applied prior to a CPES application.

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