S.S. from Santa Barbara sends me photos of an Arts & Crafts style table lamp with green slag-glass and patinated cast iron that bears no maker’s mark. It has either been rewired, or it’s a copy. Some old lamps retain their original silk cords. Does it date from the first quarter of the 20th century, which would make it valuable, or is it a copy, which we all have seen, from the 1980’s, when Victorian style decorations became the rage? S.S. asks for more information about this type of lighting, once quite revolutionary, both in its containment of the NEW electric bulb, and in the use of colored glass.
Hard to think of this style as revolutionary as we see so many stained glass lamps today. My mom’s kitchen in Illinois had a stained glass Victorian style chandelier with fruit and flowers in ugly colors made from some kind of plastic, hanging over the fake wood Formica table and the green vinyl chairs. The difference in value between a 1980’s stained glass lamp and a 1900’s original can be $10,000 or more. Although we think of the style as Victorian, it’s NOT: stained glass lamps developed with the Art Nouveau style and then merged into the more severe geometric style of Arts & Crafts.
The method of making pressed opaque glass for lampshades, like most ‘artistic’ design discoveries for the modern market, was due to a technological accident. Slag glass, which is the correct name of this early style of lampshade, looks different from stained glass. Stained glass is either opaquely, uniformly colored, OR, the color is streaked with white. Slag glass looks like marble, uneven and swirly. In fact, some of the early names of slag glass tell this story: colors were marketed as “blackberries and cream,” “purple (or blue) malachite,” or “lemon yellow giallo.” Slag glass looks like tortoiseshell, sliced thin, or malachite, with those naturally occurring swirls.
The accident that led to slag glass was the freak combination of two early 20th century industrial processes, which occurred in the late 19th century in Gateshead, England, when the young son of a glassmaker threw a bit of detritus from his other job into a vat of molten glass. He pitched in ‘slag,’ which is the stone waste matter that separates from metal during the smelting or refining of ore. At first, the resultant product was used on church windows for accent elements because it could so well imitate marble or stone. The firm of Sowerby patented a recipe for purple malachite in 1878, and experimented with the new development of table lighting growing popular in rich people’s homes for those newfangled light bulbs, putting this slag glass in shades. Each color that developed after purple called for more chemical experimentation; for example, Sowerby’s ‘blue nugget’ called for cadmium to be thrown into the molten glass in 1883.
Entrepreneurs in America discovered the popularity of English slag glass lamps: a factory named Akro Agate produced its own version, a name that references cut agate. Big named glass companies jumped on the craze, and the most expensive slag glass lamps were produced by Tiffany, Roycroft or Steuben. A fine maker’s-marked shade from one of those firms will sell at auction for over $20,000.
Bradley and Hubbard in Connecticut in the first quarter of the 20th century was known for leaded glass geometry in which slag glass was fitted into spreading shades of rich color. Handel in Connecticut was known (1901-25) for dome shades with bottom borders of leaded glass fitted floral petals. Tiffany Studios during this period in New York is perhaps the best-known maker today: the moniker “Tiffany Lamp” is ubiquitous for leaded glass lamps, and I hear the term used for all kinds of stained glass lighting. Yet a ‘good’ (untouched) and valuable leaded slag glass Tiffany Studios lamp will bear, generally, two markings, one on its shade and one to its bronze patinated base, “Tiffany Studios NY.”
S.S.’s lamp is solid and geometric and yet is a middle-class early 20th century parlor version of a more expensive lamp, because the cast iron lies on top of the slag glass, and is not fitted into the leaded geometry, as we see in the expert work of Tiffany Studios lamps of this period. At one time it would have had an interior light bulb that accented the base, and would show off the fact that your home was electrified. It’s worth $400.