Thin, long, and relatively straight cracks that form in the paint film, usually in the direction of the plywood grain.
Plywood is prone to cracking because of its method of manufacture. Plywood cracks from its expansion and contraction with changing moisture content. Stresses are induced which later show up as cracking. Many small fissures are produced in films of paints and stains that have been applied to insufficiently dry plywood. The edges of these cracks protrude upward and can be felt as sharp burrs. Subsequently, this coating may become detached from the edges of the cracks and lead to flaking.
New wood: To prevent cracking of newly installed exterior plywood, sand and immediately prime with A-100® Latex Exterior Wood Primer. Even minimal exposure to the elements will cause unprotected plywood to degrade.
Repaint: If the cracking is not extensive, clean the surface thoroughly, then sand surface smooth and wipe off dust. The plywood must be thoroughly dry. If cracking is severe, replace the wood.