Colorless Glass
Colorless Leaded Glass – Also known as potash-lead glass. First developed in England in 1676 and by the second half 18th c., was made in abundance in England and Ireland (Jones and Sullivan 1985). Contains at least 20% lead oxide. Leaded glass is relatively soft and takes well to cut decorations (All About Glass/Corning Museum of Glass). Colorless leaded glass is often referred to as "flint glass" by collectors and antique dealers.
Soda Lime Glass1 – Historically, the most common form of glass. Glass that uses soda as a flux, either in the form of plant ashes or from table salt converted to soda. Soda-lime glass is relatively lightweight, remains plastic and workable over a wide range of temperatures, and lends itself to elaborate manipulative techniques. Venetian glassmakers first discovered how to make soda lime glass colorless in the 13th century. Technological improvements in the glassmaking process at the end of the 18th century and again in 1864 made the use of soda lime glass more common. The post 1864 formula produced a colorless glass that was shiny and took well to press molding. By the end of the 19th century, soda lime glass was replacing colorless leaded glass in tableware forms (Jones and Sullivan 1985).
Manganese Decolorized Glass – Adding manganese oxide to glass balances the green color caused by iron impurities in the sand used to make glass. It has been used as a decolorizer as early as the 2nd century B.C. (All About Glass/Corning Museum of Glass). Most of the manganese decolorized glass found on archaeological sites was made between circa 1880 and the 1920s. By the 1920s, selenium became the primary element used to decolorize glass, although manganese continued to be used into the next decade.
Potash Lime Glass – Glass containing three major compounds: silica (generally 60-75 percent), potash (12-18 percent), and lime (5-12 percent). Slightly denser, but harder and more brilliant than soda-lime glass. Potash lime glass passes from a molten to a hard state more quickly than soda lime glass and hence, it is more difficult to create elaborate forms. Potash lime glass takes well to facet cutting and copper wheel engraving (All About Glass/Corning Museum of Glass).
Borosilicate Glass – Glass with a flux of boric oxide; it was first created in 1882. Borosilicate glass withstands sudden changes of temperature, so it is used for laboratory equipment, glass casserole dishes, etc. (All About Glass/Corning Museum of Glass).
Footnotes
1 On this website, any glass that glowed yellow or greenish yellow under short wave UV light was identified as soda lime glass.
References
n.d. https://www.cmog.org/research/all-about-glass. (This website has an extensive glass dictionary and thousands of photographs).
1985 The Parks Canada Glass Glossary for the Description of Containers, Tableware, Flat Glass, and Closures. With contributions by George L. Miller, E. Ann Smith, Jane E. Harris and Kevin Lunn. Parks Canada, Quebec.