 Mold etching In the 1920s a mold-etch process was invented, in which art was etched directly into the mold, so that each cast piece emerged from the mold with the texture already on the surface of the glass.This reduced manufacturing costs and, combined with a wider use of colored glass, led to cheap glassware in the 1930s, which later became known as Depression glass.Frost etching is the process in which vinyl window material is cut to produce a pattern and then applied to a window to give a frosted patterned effect.