Most Gerriets projection screens are made of PVC (polyvinyl chloride), an amorphous thermoplastic that is white, hard and brittle until it is treated with plasticizers and stabilizers that make it a malleable material useable for technical applications. Additional additives make the material flame retardant. The physical properties of PVC change with temperature, which means that PVC projection screens become more supple under heat and harden when they become cold. It is extremely important that our PVC projection screens are handled and installed at ambient room temperature, otherwise irreversible damage to the screen can occur in the form of tiny cracks in the material. Many amorphous plastics, including PVC, form small white lines when stretched, folded, or otherwise stressed. This result is called “Crazing” and creates tiny flaws that normally are not seen under normal projection conditions. However, depending upon the severity of the damage, these tiny flaws can turn into visible cracks in the projection screen.