- Q. I’m sealing an exterior wood door. What is the best finish to use?
A. For a clear finish, apply at least two coats of polyurethane to both sides and all four edges of the door after it has been beveled and planed to fit the opening. Most important, seal the bottom of the door after it has been cut and planed to fit.
If a painted finish is desired, apply the two coats of polyurethane to seal the door, then coat the door with a surface bonding agent, such as Liquid Sandpaper (General Liquids Corp., P.O. Box 5867, Baltimore, MD 21208; 410/484-7222). This agent is a deglosser that will allow the paint to stick to the smooth polyurethane.