The challenge of finishing plywood is to overcome the tendency toward face checking and coating failure as a result of the stresses induced by dimensional changes during wet-dry moisture cycling. There are basically three options:
Use a penetrating finish that does not form a surface film and therefore cannot fail by checking and flaking. High quality semi-transparent stains highlight the architectural intent of textured plywood siding. They add color and beauty to the plywood siding, showing off its rustic rough texture. The wood grain and other natural characteristics, such as color differences in the wood, show through the finish. However, be aware that repairs which have been made on the veneer face of the plywood will also show.
We recommend two coats of Diamond Vogel's Grain Stain Semi-Transparent Stain
or Grain Stain Semi-Solid Stain
be applied to rough texture plywood. Note, you need to allow time for the first coat to soak into the wood but the second coat has to be applied before the first coat dries. Any excess after the application of the second coat should be removed with a dry brush or a sponge to make sure the application is even with no lap marks. A full panel should be done at one time to keep down the possibility of lap marks.
Use solid color stains for a flexible coating when you want to cover the grain and color of the wood, as well as surface repairs, but your desire is for the texture of the wood to show through.
Use a high quality acrylic latex paint which is sufficiently flexible to withstand dimensional changes in the wood and helps to protect against the checking and cracking that occurs in the face veneer. Acrylic latex paints offer the best protection and the greatest durability for plywood