How to Treat Cypress Wood

Dry the wood before using cypress in applications like decking, siding or even as paneling in your home. Since cypress, unlike pine, is a very dense wood, if you rush the process with heat treatment you take the chance of ruining the integrity of the wood. Cypress takes time to dry -- three to five years for the absolute best lumber.

Cover the surface of the wood with a coat of polyurethane varnish using a roller or paintbrush, depending on how much wood you need to treat. Allow the varnish to dry for 24 to 48 hours so that it is tack-free. At this point it is not cured, but the thinners have evaporated.

Sand the surface of the cypress lightly with a fine 150-grit sandpaper after the first coat of polyurethane, because the application of the varnish tends to raise the grain a little. Wipe off the surface of the wood with a tack cloth, shaking it out often. If the cypress is for an exterior application, there is no need to sand between coats.

Paint the wood with the polyurethane again; this time there is no need to sand after the varnish dries. This protects the surface of the wood from moisture damage. The polyurethane takes several days to cure completely, so provide ventilation for the gasses emitted from the product as it dries. Cypress treated in this manner keeps its natural yellowed look and darkens slightly after the sealing process.