We got a couple of custom formica countertops made about three years
ago, but they've only been in use two years. They have a bevel on the
front edge. So the beveled part is made up of a piece of formica maybe
3/8" wide.

At one edge, near the sink naturally, the seam has widened. Presumably
water got into the seam and swelled the plywood underneath. Is there
any way to undo the damage, i.e. UN-swell it? Failing that, can I
"seal" it somehow so it doesn't get worse? It's not that noticeable
yet, so if I could seal it and color in the slight split to nearly
match the formica I think it might be OK.

Ideas?

Greg Guarino