Sur-Seal Inc. 7530 Virgin PTFE (polytetrafluoroethylene) is a high molecular weight polymer and one of the most versatile plastics known to man. Sur-Seal Inc. 7530 Virgin PTFE sheet can handle virtually all chemicals in the 0-14 pH range with the exception of molten alkali metals and elemental fluorine. It is suitable for service at temperatures from the cryogenic range up to 500F.