Shedding Light on "sun purple" Glass
  by Elaine Henderson
Reprinted from All About Glass,
the magazine of the 
West Virginia Museum ofAmerican Glass, Ltd.
The Voice of the Glass Collecting Community.
     During the mid and later 1800s virtually all American glass companies were using manganese in their glass formula. Around 1915 the use of manganese was discontinued and selenium became the chemical of choice as a clarifying & stabilizing agent.
      After the change in chemicals, the appearance of the glass seemed at the time, to be no different. But that was nearly 100 years ago. It is not known when the difference in the “tint” of the glass made before & after selenium, became apparent. But eventually it was noticed that if pre-1915 pressed glass was left in a sunny window over a period of years, it took on a grayish pink or lavender hue & so wise owners of the older glass learned to store and display their glass out of direct sunlight to prevent “discoloration”.
       At some later unknown time, someone realized what was causing the glass to “discolor”. It was the sun! And so, a few dealers, probably here in the “Sunny Southwest”, not realizing they were causing a detrimental and irreversible change in the glass, began to speed up the turning of the glass color by placing the dishes in the sand or on the roof so that it got the full time sun and they began to market the glass as “sun glass” or “sun purple” glass.
       Then someone realized that the agent that did the color turning was actually the ultraviolet rays of the sun. Voila! They no longer needed the sun to turn glass purple to appeal to the “folks up North” (their words) who had become intrigued by purple glass from the “sunny southwest”. The marketing of the “sun purple” glass was so successful that the sellers took it down off their roofs and put it into boxes with a lamp that gives off UV rays and made the color change in weeks instead of months. That instrument of choice was & is a lamp intended to kill germs.
       Over the next dozen or so years, the fad for “sun purple” glass spread. According to a 1974 article, a couple said they had been “collecting and sun coloring glass for about 20 years, and have accumulated thousands of pieces.” So for over 30 years the sellers of it have reaped high prices for their minimal efforts of putting any glass dishes which glowed under a black light (signifying it contained manganese), into the germicidal boxes for a month or so.
       About 10 or 12 years ago, some EAPG enthusiasts began to realize that it was getting out of hand! Large quantities of sickly purple EAPG were showing up in antiques malls and flea markets, especially in Arizona, New Mexico and California. The practice is an anathema to EAPG collectors and a move to stop it was attempted because the practice is irreversible and, as the years pass, fewer pieces of 100+-year-old EAPG remain on the market due to breakage.
       And now, there are other color altering methods. Apparently a month is too long and light amethyst isn't deep enough and so the practice of using some sort of x-rays to turn glass other colors, including deep amber and deep amethyst has begun. Collectors of early glass other than EAPG, such as bottles and insulators, are experiencing the same phenomenon. Caveat Emptor takes on an expensive meaning when collectors fall for the line that a piece of glass has been found in a “newly discovered” color.
       It is a daunting task to educate the buying public because it is difficult to reach individual buyers who have no idea what they have bought into and sellers are adamant (even hostile) that they have no intention of stopping the practice as long as “it sells”.
A good analogy is the practice of taking a piece of Pennsylvania Dutch hand-painted furniture, stripping it down, painting it red, white and blue and calling it “patriotic”. Or spray paint a piece of rare art glass black. Sure, everyone has the right to do what they want with what they own, but to destroy the integrity of a piece of American history, as this 100+ year old glass is, serves only to diminish this National Treasure.
       One of the reasons given for purchasing “sun purple” glass is that folks who do not know how to tell the age of glass can be assured that the glass they buy is “old” if it is purple. An appropriate response to this argument is - that is tantamount to taking a clear plate and throwing it on the sidewalk & if it breaks, you know it was glass & not plastic. And to make that reasoning even more untenable, modern day glass companies are now marketing EAPG reproductions in what they call “antique amethyst”! So color is not a fail-safe way to tell the age of glass and actually the new amethyst color is prettier than the turned antique glass!
       Glass Collectors and professionals who live back east don't see the shelves full of the ruined pattern glass. But we in the southwest do. We were in one antiques mall in California in which every booth displayed dozens if not hundreds of pieces of “sun purple” glass. And this past February, we visited the shop of a woman who advertises herself as a “Pattern Glass Specialist”. When we entered her shop, we were stunned to see shelf after shelf of rare pieces of EAPG all turned purple. When we registered our dismay, she countered that she, at one time had over 7,000 pieces of it and had more turning in her box as we spoke. Other booths in town had a staggering number of similarly discolored pieces.
       To add to the confusion, an early book on pattern glass reported that the color change is reversible. This is not true - several have tried it lately and the color reversal only takes place at the temperature that melts or seriously crazes the glass.
       We hope that you will join in the dismay of knowing that thousands of pieces of pattern glass have been and are being virtually destroyed as an antique for posterity. Because the dealers who are turning glass purple are defiant, we only have one choice and that is to educate the buying public that EAPG is beautiful, useful and charming just as it was created in the century before last.
       To that end, we encourage you to download this Fact Sheet
and hand it to antique mall and shop dealers as you shop. There is no need to be confrontational, just let the facts speak for themselves.
For more information on this subject, please see click HERE.

Elaine & Bill Henderson are charter members of the national Early American Pattern Glass Society; National American Glass Club, Ltd. and National Greentown Glass Association, Inc. members, and own, a pattern-matching service exclusively for EAPG tableware (and some related Victorian novelties) ca 1850-1910.
Visit the Victorian Pattern Glass Store by clicking HERE