Tim, Polyester releases well typically because it shrinks as it cures,, another issue is the first few parts out of a molde tend to be really prone to sticking,, IMHO,, and limited experience on our aircraft parts.. and if you spray the PVA like it was paint, you can lay it down with minimal affect on the finish,,,
On a related note,, I never heard of using PVA for force curing the exposed surface on polyester,, great idea,,