The first think I do wax the plug and parting board with Johnson paste wax. Let it dry and buff it off. Do this 3 times. Then time for PVA release agent,2 coats.
The surface I use is a aluminum fill epoxy surface coat. There is 2 coats. Let the first one dry to the touch just to leave your finger print in it. Then put on the next coat of surface coat. I do not let it start dry i start putting my fiberglass on. I do a 2 layer of 2oz ,then a layer of 4oz,and then a 1 layer of 6oz. Around the bolts I use to bolt it together,I mix up a batch of epoxy and cotton flock and Thixotropic Silica cabosil.This help hold up to all the bolting together.