I am in the middle of finishing an edge glued pine top 21"x52"x3/4". So far I have dye stained (water) top and bottom, one coat of General Finishes black acrylic paint around perimeter of bottom side and two coats on the top side. When I finished yesterday the top had cupped severe enough that it was easily noticed. This morning it has flattened back out about 95% to where it is acceptable. Now I plan to distress it lightly, glaze it (Generalís wb glaze) and finally top coat with Campbellís Aqualente. I am concerned about the cupping coming back. Should I even out the coats top and bottom with the black as well as the clear coat or is there a better way?
From contributor B:
There are two things you can do. You can put braces across the bottom, going cross grain, or use pine plywood. I would use the plywood, end of problem.
The solution is to prevent uneven moisture, top and bottom. Then you will not have this cupping. Note that the idea of alternating the grain of individual pieces is often given as a solution, but the benefit of such altering is very small. Wetting one side and not the other with a WB finish will create such a difference, face to face, that the piece will be unsatisfactory even if the grain alters. It is really rare, especially with softwoods that do not move much compared to hardwoods, for commercial operations to alter. They know that if the MC is OK, then this extra step is a waste of time.