CPES is basically just thinned out epoxy that will soak into the wood. It penetrates and makes it waterproof. Brush on, let soak in, then repeat. Then I brushed on a thicker layer of epoxy on the bottom, waited for it to dry and then installed it. I brushed on a final layer of epoxy on the top, then laid down wetted fiberglass matte and brushed epoxy over the top of it. I only used a single layer of the matte for the floor.

http://www.star-distributing.com/smith/cpeswhy.html