Quote Originally Posted by bobberly1 View Post
... My only concern with finishing the top side is flammability, these finishes are combustable dried, are they? They're going to be in contact with flexwatt, so this is a major concern...
Well, I'll throw this in... birch plywood is combustible too. Presumably, you will be using a thermostat on your rack to control the heat put out by the flexwatt, and it shouldn't ever get to temps much over 100 degrees f. Not high enough to worry about combustion. Your main worries about finish is toxicity, and then mainly for the uncured finish. Finish it how you like, but make sure to allow it to cure completely before putting animals in.

Steve