Dating antique stained glass


The purer the sand (i.e., the higher the silica concentration and less iron) the better, as it is the other impurities - desired or undesired - that give glass its color.



Adding to the confusion is the jumble of terminology that is used to describe colors and the almost infinite color variations.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.There is a very broad chronology of popularity of various colours over time; however that chronology cannot be applied to individual glass objects with any significant level of meaning..."The majority of common bottle glass is "soda-lime glass" which is primarily composed of silica, soda (aka soda-ash) or potash, and lime - the latter two ingredients often referred to as the "alkalies" (Hunter 1950; Toulouse 1969; Munsey 1970).

The silica (silica dioxide) typically makes up 60-80 % of the glass composition and is primarily derived from sand.

As noted on Greg Spurgeon's fruit jar oriented website there is no "governing authority" on glass or bottle colors (Spurgeon 2004).