Photoglass: Photomasks are the master tooling used by chip manufacturers and other industries to optically transfer patterns onto wafers and other substrates. Photomask plates are made of high-purity quartz, borofloat or sodalime glass that has been polished to micron flat tolerances. These glass plates are uniformly coated on one side with a very thin layer of metal such as chrome or iron oxide. This thin layer of metal has a uniformed photosensitive compound called photoresist applied over the entire metal layer. The finished product is called a photomask blank.