Vitreous marble

Black Vitrolite panelling on the Daily Express Building in Fleet Street, London.

Vitrolite was an opaque pigmented glass manufactured by Pilkington Brothers in the United Kingdom. It was made by The Vitrolite Company (1908–1935) and Libbey-Owens-Ford (1935–1947) in the United States.

The same structural pigmented glass was marketed as Sani Onyx (or Rox) by the Marietta Manufacturing Company from 1900 onward and as Carrara Glass by the Penn-American Plate Glass Company after 1906. The latter brand is named for the white or blue-grey Carrara marble, a structural veneer from Carrara, Tuscany, Italy for which the pigmented structural glass represented a lower-cost alternative.^[1]

The term vitreous marble was used by Marietta Manufacturing as a generic identifier^[2] for pigmented structural glass, although the genericised trademarks are in common use.

The introduction to Vitrolite Specification, published in 1938 by Pilkington Brothers, stated that Vitrolite was a rolled opal glass, ranging from semi-opacity to complete opacity. One surface was usually impressed with a pattern of narrow parallel ribs which provide a key for the mastic or other material with which the glass is fixed. The glass had a hard, brilliant, fire-finished surface.^[3]

Architectural characteristics

The material was available in various colours, blacks and whites. Architect Cass Gilbert adopted it in the interior design of the Woolworth Building (1912-1913) in New York City. Used for internal and external tiling and façades of buildings from the 1920s to the 1950s, it is often associated with the streamlining of the Art Deco and Art Moderne movements. Its polished, slick and shiny surface could be curved, textured, sculptured, cut, laminated, coloured and illuminated; it could also be readily retrofitted to existing buildings as part of efforts to "Modernize Main Street" in the Great Depression era.

Vitrolite tiling at Eglinton station in Toronto.

Because vitreous marble is glass, it shares the benefits and problems of glass. Due to it being a non-porous substance, unlike marble, it does not harbour bacteria; it therefore was used extensively in bathrooms and kitchens as a substitute for marble counter tops, table tops, wainscoting, and restroom partitions. It is a delicate substance, breaking easily and became obsolete with the emergence of cheaper and more durable substances.

Vitreous marble has not been manufactured in the United States since 1947, although glass companies near Bavaria, Germany were producing an opaque pigmented structural glass "Detopak" in small quantities with similar characteristics for much of the remainder of the twentieth century.^[1]

References

External links

• Vitrolite Specialist Historical information and images, as well as preservation tips.