Glass-fiber fabric coated with PTFE (polytetrafluoroethylene, also known as Teflon) is regarded as one of the most durable membrane materials because the coating is self-cleaning and very resistant to chemical substances and mold growth. Newly coated material is initially beige in color but fades after erection through the decomposition of the wetting agent in contact with UV rays. This process takes approximately 2-3 months in Northern Europe, a correspondingly shorter time in regions with higher levels of solar radiation.The PTFE coating is chemically inert, withstands temperatures from minus 73°C to 232°C, is immune to UV radiation and can be cleaned with water. PTFE-coated fiberglass is available with as much as 25% translucency, providing diffused interior light. Its ability to allow natural daylight and provide night time interior lighting can reduce energy consumption. Coated and Uncoated PTFE fabric:This material is constructed of PTFE fibers woven into a fabric. Woven PTFE combines the environmentally-resistant advantages of the material with its ability to withstand repeated flexing and folding, an advantage it has over coated-fiberglass, therefore PTFE fabric is frequently used for high quality watertight retractable membrane roofs. It is characterized by its high flex cracking resistance, light weight, high light transmittance and anti-adhesive surface.