What are you trying to make? The products mentioned in the previous post are what you should be using to insure a successful release. There are several different mold release waxes out there, here are a couple I've experimented with. The PVA is used with the wax, not alone (typically).

I've actually tried some car waxes years ago, but almost every time it "pre released" on me defecting the part. Way too slippery from the silicone. Mold wax has no silicone and is made with carnuba. It dries hard and dosen't leave an incompatable greasy film on the surface.

Get the right stuff in the beginning......you'll most likely are buyng it down the road. Oh, you can buy PVA in half pint sizes either online or locally at most marine parts places like West Marine (if you have one).