ISO 13000-1:2005 specifies the requirements for processed unfilled polytetrafluoroethylene (PTFE) products which may occur in several forms. The PTFE used to make the semi-finished product is described in ISO 12086-1 and, as provided in ISO 12086-1, may contain up to 1 % of a comonomer. The PTFE used to make the semi-finished product may be virgin, reprocessed or recycled resin. The addition of up to 1,5 % by mass of pigment or colorant is permitted. This part of ISO 13000 allows for four grades based on tensile strength and elongation at break. The semi-finished products can be as-processed (type P) or dimensionally stabilized (type S) and may also have specified electrical properties or other properties when they are required for an application.