What causes alligatoring?  Is it expansion and contraction of the wood?  If so, I thought wood would do that across the grain, instead of with the grain?   Why are the alligatoring lines across the grain, instead of with it? The greatest movement of the wood is parallel to the grain, NOT!  The greatest rate of shrinkage from the green state and movement from moisture cycling is tangential to the growth rings. The second greatest is radial (perpendicular to the pith) and the LEAST (often considered negligible) is parallel to the pith line or linear. So, Professor Norman Einstein of Forest Products, YOU explain it. Are you characterizing the cracks in paint as perpendicular, parallel or what to the tangents of the growth rings.  And in what direction relative to the length of a board do these tangents run?  Do the effects of moisture movement, shrinkage from green state, and thermal expansion all operate in the same direction? ….causing stress in the paint and crack formation perpendicular to the motion, as the paint expands and contracts. Was it alligatoring in the paint or in the wood fibers? It was the paint. Whoever heard of alligatoring wood?  Although it gets alligatory cracks perpendicular to the grain when it burns, too, now that I think about it. What's your explanation of that? . I think. We can argue about that later. Why not now?

 

christopher Ralph Rudy