I believe that Peel Ply is a product from boat fiberglassing. West Systems calls it a "release fabric" also known as Peel Ply.. I'm pretty sure that one guy using it on his planes learned it from working on boats. However, I think that the "peel ply" used on full size boats is probably a bit heavier than the polyester we use.

Yes, I go to the fabric shop and buy 100% polyester dress lining.