Color Bars: Bars of concentrated colored glass about 1” in diameter and a foot long. The glassblower cuts these in smaller chunks to melt, crush or overlay the softened bar over a bubble. MoG purchases color bars from Kuegler (Germany) and Gaffer (New Zealand). The glass is colored with different metal oxides, which are the same elements used to pigment paint. Cobalt makes blue, iron for green and sometimes brown, selenium for yellow, cadmium for red. Gold is also used for certain shades of red.

Color Oven: Any small kiln (or corner of the annealer) used for preheating chunks of color bars to about 1000˚ F to allow pickup without cracking. There is usually a blackboard near the Color Oven to plot the layout of the various colors it contains.

Enamel: A vitreous substance made of finely powdered glass colored with metallic oxide and suspended in an oily medium for ease of application with a brush. The medium burns away during firing in a low temperature kiln.

Glass-painting colors: Subdivided into cold and firing colors. Cold painting entails applying the paint (watercolor, tempera, oil, lacquer paints, etc.) and letting it dry, which is not very durable. Colors for firing are subdivided into four groups: 1) enamel (opaque enamel, transparent enamel and flat colors); 2) precious metals (bright or gilt painting, silver or platinum); 3) Stain 4) Luster pigments. Firing colors are applied, dried and then fired in a muffle kiln at temperatures between 965˚ F to 1300˚ F. They are of highly variable durability, depending on how they bond with the surface of the glass. Stain is the most durable form, and luster is the least durable form.