Painting MDF or particleboard creates smooth surfaces on the faces of these sheet goods but not on their sawn edges. The edges are much more porous and soak up paint like a sponge. To remedy this, I thin joint compound for drywall with a little water and rub it into the edge with my finger. Then I lightly sand it. The joint compound seals the edges so they absorb paint more similarly to the smoother faces.
– Randy Wolfe
Hoover, Alabama
