Perhaps you've gazed in admiration at all the rainbow-hued colors that Mosser cats come in and wondered how these stunning colors were created. Well, you're in luck! In this section, we're going to cover what goes into making colored glass.

Mixing colored glass is an art form in and of itself. Colored glass gets its color from intentional additions of elements, metals and compounds. Most glass companies in the past had a book of closely guarded formulas that showed the precise chemicals used and the amount needed to achieve certain colors. An expert glass mixer is worth their weight in gold. Years of experience have given them the knowledge to use just the right amount of minerals and elements to create certain colors. 

Each batch of glass is mixed entirely by hand. If too much or not enough of an ingredient is added, they end up with a color that's too light, too dark, or not even the right shade. Just like baking a cake, the ingredients must be properly measured and mixed. Being able to deliver uniform batches consistently is key to producing high-quality glass. Pressed glass ingredients include lyme, sodium nitrate, soda ash, silica sand, mineral or chemical colorants, and leftover glass from the factory. The chemical composition of the glass also plays a large role in the colors produced by additives.

Some challenges that can occur while coloring glass are impurities such as iron or sulfur compounds. These can greatly affect the clarity of the glass. To rectify this, a decolorizer is used to remove them, so the glass starts out clear. Two common decolorizers are manganese dioxide and cerium oxide. Do you ever notice how dark antique glass bottles are? These are the byproducts of glass created without decolorizers. This early-produced glass got its color either from natural impurities in the sand used to make the glass or the smoke from the coal used to melt the sand. An example would be the dark green to nearly black “black bottle glass” from 17th-century England. It got its color from iron in the sand and sulfur in the coal. 

Did you know that you only need less than 1% of the added elements, metals and compounds mix to colorize glass? As long as it's blended thoroughly, the colorization process will be successful. The image below lists elements, metals and compounds that color soda-lime glass. Keep in mind that the ingredients may also be mixed to create intermediate colors. Also, the transition metals display several oxidation states, so a single element may create multiple colors, depending on conditions.