Purple Sun Glass was manufactured at the turn of the last century, up to WWI. Prior to the Civil War, clear colorless glassware was made with lead, but lead was needed for warfare. Subsequently the lead was replaced with manganese dioxide in the manufacture of soda lime glass, producing a crystal clear product more desirable than the greenish color that resulted without the use of lead. Glass makers added manganese to decolorize the glass from aqua green, a hue imparted by iron contamination of the sand used in making glass.
While their intention was not to impart a purple tint, over time and with exposure to ultraviolet rays of sunlight, the manganese in the glass caused a permanent color change to a light purple. The subsequent color shift to light purple after months or years of exposure to sunlight was both unexpected and unintended.
While purple sun glass, or amethyst glass, dating to as early as 660 BC was found in Egypt, modern manganese glass was manufactured from about 1865-1920 [Historical Archaeology 2006 40(2): 45-56]. Items manufactured from this glass are now collectable antiques ranging from glass electrical insulators and transom windows, to common and fine glassware. Even glass medicine bottles of the period turned purple as they lay discarded in old dumpsites. Purple sun glass items were made for everyday use, therefore many that have survived show signs of wear such as scratches, fleabites, and chips. Nevertheless, they remain highly collectable.
Thomas Gaffield in 1881 described the action of sunlight on glass as
painting by the magical pencil of the sun.
I have been collecting purple sun glass items for about 40 years.
Some of these items are featured for your admiration and for sale in the
Purple Sun Arts Studio and Gallery
142 Harrison Street in Oak Park, IL.