The lip piece is a GFA also, but the envelope is made of plastic cap material, the same blend of polyvinyl acetate that bald caps are made of. Thesame mixture of silicone gel (Polytek Plat Sil Gel 10 with a high percentage of softener) is encapsulated between thin layers of bald cap material. By encapsulating with cap material, we can easily blend the edges off to nothing using a small brush and
99 percent IPA.