The Rot Doctor


Subject: CPES + topcoat? (on outdoor table)
Date: Sat, 25 Oct 2003

Your CPES™ sounds like just what I'm looking for, but perhaps not the whole job?

I have a slab of redwood, nicely finished on one side, that I'd like to use outdoors as a table top. I want to protect it, and was considering epoxy gym coat, when I found your page.

Your CPES™ sounds like just the material to stabilize the wood, but not the material to provide a top finish, though I may be misreading it. Are a few coats of CPES™ a suitable final finish for long term outdoor exposure? If not, what do you suggest?

-David G.


CPES™ is a fine preliminary coating for your table top. A couple of coats (including the edges) would be sufficient.

The real issue here is the final coating. CPES™ is an epoxy, and like all epoxies it is gradually degraded by UV light. The wood remains protected, but the surface turns light gray. In the boating community they solve this with 3-5 coats of a marine varnish, which contains UV inhibitors to protect the epoxy base and the wood. Done this way, your table would be quite attractive.

Your alternative would be to simply coat with a urethane, such as Varathane. This will look fine for awhile, but again the UV light will gradually break down the surface and start to discolor the wood.

CPES™ plus varnish is your best alternative, as long as you understand that every year the top surface will have to be lightly sanded, wiped down, and have a new top coat of varnish applied.

If using CPES™, try to get the first coat of UNCUT varnish on the surface as soon as the CPES™'d surface becomes tacky, or within 12 hours. This way the curing epoxy will "lock in" the initial coat of varnish.

Do not use an epoxy "gym coat" or anything like it, because these are for indoor applications only, where there is very little if any UV light.

Hope this is some help, and feel free to come back if you have additional questions.