Carbon dating in archaeology
Bottle colors also warrant coverage here simply because they are of fascinating interest to people.As implied in the quote above, there are some time related trends in color that can be of utility for dating. The specific "diagnostic utility" of a given color is noted in the descriptions below.
This is just informational because the actual chemistry is of little utility and glass colors only contribute a little to the process of dating or typing historic bottles.
So called "natural" colors are those that result "naturally" from the basic ingredients in a glass batch (Mc Kearin & Wilson 1978).
In general, with lesser amounts of iron or less oxidation of that iron, shades of bluish to greenish aqua are achieved.
Many colorizing compounds work in different ways depending on whether the glass pot environment is oxidizing or reducing (Tooley 1953; Kendrick 1968; Toulouse 1969).
However, discussing the simple addition of chemical additives makes any discussion of glass making and glass coloring too simplistic.