The Waterproof Membrane is a crack bridging sealant membrane made of soft polyethylene. It has water vapor retarding properties and is physiologically safe. Because the waterproof membrane does not require disposal as special waste, it is also environmentally compatible. The mats are fabricated with a fleece fabric on both sides which provides maximum anchorage in the tile adhesive. The Bright Ideas Waterproof Membrane is highly elastic, waterproof, resistant to aging and rot proof. It is also resistant to aqueous and chemical solutions, salts, alkalis, alcohols, oils and organic solvents.