Q: Is it necessary to prime plywood before painting on it
with oil? Couldn't I apply a layer of oil paint directly to the board,
let it dry, and then start painting on it?
A: Painting directly on plywood can prove problematic.
Plywood is porous and contains natural oils that can cause problems
with your oil paintís curing process. True drying time for oil paint is
one year, although some pigments dry faster when painted thinly. On
bare plywood, however, your artwork will not be archival, so it is best
to prime your plywood to protect both the wood and your artwork.
--by Camille LaPointe-Lyons