Glass can come in many colors. The ingredients that account for this phenomenon are varied, though the basic elements of glass never change. These are, simply; sand, soda (from wood ashes) and lime (crushed limestone). It is the addition of certain different elements to this basic formula that account for color variations. In this scroll, I will discuss these components, and the colors they produce, and the various different uses of colored glass.

Although most people believe that glass is naturally colorless, any glass smith would tell you differently. This is because glass is actually an aqua, or blue green color when it first comes out of the boiling pot. The reason for the green shade of the glass is because sand, which is the most important ingredient in glass, contains traces of a metallic element called iron oxide, and it is the iron content that is responsible for the green color of the glass.

To make a colorless glass has been the goal of glass smiths for many turns. To do this, many different formulas were used. The most successful of the earliest expirements were through the use of crushed quartz, ground flint, and red lead, but all of these items were to time consuming to mine, thus making the glass too expensive to make. So the search went on for the formula. Finally, the best method was found using either Selenium, or Manganese. Both of the elements worked well in bleaching the glass, and were cost effective. So colorless glass became relatively inexpensive and easy to produce.

In the process of learning ways to bleach glass, other colors were discovered, using different ingredients in the basic glass formula. Among the most popular was the use of iron slag, which produced a very dark green, almost black color, carbon for dark green and brown glass, and clear true colors made with the addition of different metallic oxides to the mix. These are cobalt for blue glass, chromium or sulfur for yellow and green, nickel for purple, copper for gold or red, and tin or zinc for milk glass, which is a creamy, opaque white color. The use of these oxides is rare, howver, as they are costly to mine.

Another discovery in making colored glass occurred quite by accident. Previously I mentioned that Manganese was used to create a clear, colorless glass. But it also became the most popular way to make a clear purple glass, as well. It was discovered that the combination of iron oxide and manganese, exposed to ultraviolet rays (the sun), causes glass to take on a rich purple color, the intensity of the color determined by the amount of manganese used. This is why you will see more purple glass than any other color except for straw, or amber glass, and of course, the green glass. Selenium, also used to bleach the green tinge from glass, also exhibited a color change phenomenon when combined with iron oxide and ultraviolet rays. If left exposed, the glass would turn amber in color (pale goldy yellow). Manganese and selenium are the only two elements that seem to have this ability to change color, however.

Both colored and colorless glass are popular items, either for their beauty or practicality, which is evidenced by the examples listed next. For things like champagne (bubbly wine), a dark green bottle is desired. For glassware, clear is popular. Brown is used primarily by the healer hall, because it tends to lessen the exposure to light of medicines, making them last longer and be more effective. The more expensive colored glasses are in great demand by lords and ladies as ornaments and perfume holders. And lastly, brightly colored glass is used quite often in poison bottles, to make them stand out. All of the above uses are important, some more than others, like the glass for medicines and poisons. But each and every color has its own history, and beauty, no matter what the need for it is.