Flaking is the lifting of paint from the underlying surface in the form of flakes. It is generally preceded by cracking or checking and will occur over different surfaces. When it occurs over wood, it is usually found on those boards that have an excessive amount of “flat” hard grain pattern. This flat grain pattern is smooth, hard and non-porous. Highly pigmented paints crack and eventually flake when applied to this type of surface. They cannot accommodate the large extremes of expansion and contraction of the wood that are caused by seasonal weather changes. Because of poor paint penetration into the hard flat grain, flaking will occur on these areas.
 

A light sanding to fresh wood followed by application of a high quality under-coater is recommended. Wood must not be allowed to weather prior to coating. Replace boards that have an excessive amount of flat grain patterns with boards that have an edge grain (e.g., boards with equal amounts of narrow hard and soft grain patterns).