Pigmented structural glass

Pigmented structural glass[lower-alpha 1] was developed in 1900 in the United States by the Marrietta Manufacturing Company of Indianapolis, Indiana.[2][3][4] The product was made by combining borax,[5] cryolite, kaolinite, manganese, silica,[4] feldspar,[6][5] and fluorspar.[6][5][lower-alpha 2] The fluorides made the glass opaque.[1]

These materials were fused[6] into glass at a temperature of 3,000 °F (1,650 °C)[4][5][8] and then annealed.[4][8] The annealing process took much longer than it did for plate glass, often lasting three to five days.[4] This left the glass very strong, with a compressive strength about 40 percent greater than marble.[9] If the product was to be affixed to another surface (such as the exterior of a building), one side of the slab was grooved before the glass hardened.[10]

The exposed side(s) of the material was flame polished,[4][8] which left the product highly reflective and brilliant.[9] Later manufacturing techniques used fine sand to polish the surface, followed by felt blocks and iron(III) oxide powder.[4]

Originally, only beige, black, and white colors were available. But by the 1930s, new manufacturing methods could make pigmented structure glass translucent, and more than 30 colors were available.[2] In time, even agate- and marble-like color patterns were available.[11] Black structural glass was sometimes silvered, to give it a reflective finish.[2]

Pigmented structural glass could be manufactured in flat panels or curves, and in a wide range of sizes and thicknesses.[2] Small mosaic tiles, affixed to flexible fabric, were another option for fitting the product to curved surfaces.[2] In time, manufacturers learned that pigmented structural glass could be carved, cut, inlaid, laminated, sandblasted, and sculpted to create a wide range of finishes and textures. When translucent, it could be illuminated from within.[3]

Vitrolite tiling at Eglinton station in Toronto.

Pigmented structural glass was originally marketed under the name "Sani Onyx" by Marrietta Manufacturing.[3][4] The company also used the name "Sani Rox",[3] while the term "vitreous marble" was coined by the firm as a general descriptive.[12] By 1906, the Pittsburgh Plate Glass Company had developed its own pigmented structural glass, which it called "Carrara glass".[13][lower-alpha 3] The same year, the Penn-American Plate Company began making a pigmented structural glass which it called "Novus Sanitary Structural Glass".[13] In 1916, The Vitrolite Company began manufacturing the product under the name "Vitrolite",[13] which eventually became a generic name for pigmented structural glass.[2][lower-alpha 4] In time, about eight American firms made pigmented structural glass,[2] although Carrara glass and Vitrolite dominated the market.[2][15] Names used by these and other companies to market the product included "Argentine", "Glastone", "Marbrunite", "Nuralite", and "Opalite".[4] Pigmented structural glass was also manufactured by Pilkington Brothers in the United Kingdom.[2]

Marrietta Manufacturing originally marketed pigmented structural glass as a lining for refrigerators. Industrial consumers quickly found new uses for the product as countertops, dados, bathroom partitions, storefront signs, and tabletops.[2][3] By the early 1920s, it was advertised as an inexpensive alternative to marble or ceramic tile.[6] The Art Deco and Steamline Moderne architectural movements vastly increased the market for pigmented structural glass.[16] Its first important architectural use came in 1912, when it was used for bathroom stall partitions and dados in the Woolworth Building in New York City.[2] By 1929, 5,000,000 square feet (460,000 m²) of pigmented structural glass was being manufactured in the United States.[4] Throughout the 1930s, the product also found a use as cladding for storefronts, entryways, lobbies, and even as ceiling material. It was seen as an inexpensive means of making a dated building look modern.[2][3]

The Great Depression significantly reduced the demand for pigmented structural glass. American production reached only 1,000,000 square feet (93,000 m²) in 1933.[17] By the 1950s, changing architectural tastes had vastly reduced the demand for the product.[4] The last two American manufacturers ceased production about 1960: Libbey-Owens-Ford shut down its pigmented structural glass plant in 1958, followed by Pittsburgh Plate Glass in the early 1960s.[4][18][lower-alpha 5] Production continued in the United Kingdom until 1968, and in Bavaria, Germany, until the end of the 20th century.[19]

Unlike masonry, pigmented structural glass does not craze, swell, or warp. It is highly burn and stain resistant, and is colorfast. Since it is a glass, it is impervious to moisture.[20] It cannot absorb pathogenic bacteria, viruses, pathogenic fungi, or parasites, and is easy to render aseptic.[21][22]

Notes

Citations

• Dyson, Carol J. (1995). "Structural Glass". In Jester, Thomas C. (ed.). Twentieth-Century Building Materials: History and Conservation. New York: McGraw-Hill. ISBN 9780070325739.
• Esperdy, Gabrielle M. (2008). Modernizing Main Street : architecture and consumer culture in the New Deal. Chicago: University of Chicago Press. ISBN 9780226218021.
• Kappos, Ludwig (1987). Preservation Briefs 1-14: Recognizing and Resolving Common Preservation and Repair Problems Prior to Working on Historic Buildings. Washington, D.C.: U.S. Government Printing Office. ISBN 9780160035487.
• Kious, Kevin; Roussin, Donald (2012). Breweriana: American Beer Collectibles. Oxford, UK: Shire. ISBN 9780747810445.
• Parker, Harry; Hauf, Harold Dana (1977). Simplified Mechanics and Strength of Materials. New York: Wiley. ISBN 9780471665625.
• Pender, Robyn; Godfraind, Sophie (2011). Practical Building Conservation: Glass and Glazing. Farnham, Surrey, England: Ashgate. ISBN 9780754645573.
• Piazza, Gregory; Machielse, Allan; Austin, Dan (2015). A History of Detroit's Palmer Park. Charleston, S.C.: The History Press. ISBN 9781626197848. OCLC 907885624.
• United States Department of the Interior (2004). The Preservation of Historic Architecture: The U.S. Government's Official Guidelines for Preserving Historic Homes. Guilford, Conn.: Lyons Press. ISBN 9781592281268.
• "The Vitrolite Company: Sanitary Structural Slabs". Sweet's Architectural Catalog. 15th Annual Edition. New York: Sweet's Catalogue Service. 1920.
• "The Vitrolite Co.". The Modern Hospital Yearbook. Chicago: The Modern Hospital Publishing Company. 1919.