What I do:
- Sand to desired shape (never leave sharp edges)
- Blow with compressed air or vacuum out edge of ply (dust-free is best)
- Apply one good coat of epoxy and let it cure
- Sand to smooth, vacuum or blow with compressed air again
- Mix up some epoxy thickened with silica (Cab-o-Sil etc) and using a gloved hand, smear the thickened epoxy into/onto the edge of the wood. Make sure all holes are filled and that you leave it relatively smooth (close to a finished smoothness). Let cure.
- Sand edge of plywood to smooth out any goofs with the silica-thickened epoxy, vacuum/blow/wipe to clean it.
- Apply final (1 coat typical) coat of epoxy.
I find that sealing the ply with a coat of unthickened epoxy, followed by filling with silica-thickened epoxy, then finished with a final coat of epoxy is the fastest route to getting the job done and results in a plywood edge that is very waterproof, smooth, and used minimum epoxy and supplies to do it.
Brian
