What is the best method to varnish over wooden surfaces that have been sealed and faired using epoxy?
Sue and Larry respond:
- The procedure for varnishing over epoxy is not substantially different from varnishing wood. When epoxy cures properly, it becomes inert. The first step is to varnish a test area on the epoxy to ensure that it cured properly and exhibits inert characteristics. Wash the surface and then sand with 150 to 180-grit sandpaper. Apply unthinned varnish to the test area and wait until the next day. If your varnish dries correctly, everything's OK. If your varnish doesn't dry, there's probably a problem with the way your epoxy cured. In this case, contact your epoxy manufacturer's technical department.
Gougeon Brothers, the manufacturer of WEST System epoxy, suggests three coats of epoxy followed by three coats of varnish to yield a finish equal to 10 or 12 coats of varnish. Epifanes or Schooner varnish should both perform well. Since your epoxy will not soak up any of the varnish like wood, you can apply the initial coat unthinned, and like your test area. Prior to applying your first coat, sand the area with 150 to 180-grit paper.
Other than these differences, simply follow the procedures for applying varnish over wood.