Hi Chris,

 

The PVA works pretty well but what I don't like about it is the way it beads up on a waxed surface so when it's a hot day, it's OK to mist coat the PVA then apply more as it builds up thicker.  But what I REALLY liked was a product called PV6 from Finish Kare.  It was like a solvent based PVA that didn't bead up.  It also gave a mirror shine so you didn't have to do perfectly glossy parts to get a glossy mold.  Unfortunately they went bust so I don't know of a replacement.  And PVA was NEVER used on the inside of a "real" mold since it left a fairly crappy finish with orange peel.  But it certainly would keep the resin from sticking to Bondo so that is a viable option.

 

So I still keep the PVA stuff around and use it from time to time but I still prefer Duracote/featherfill.  Did you know that PVA also is very handy to keep air from getting to your polyester resin and gelcoat?  Instead of adding wax into the resin of gel, you can spray over the top of the wet resin thus blocking air from getting to it.  The resin turns hard and sands well without the usual gummy resin crap that clogs your sandpaper.

 

Dan