terra-cotta(Italian; “baked earth”)

Fairly coarse, porous clay that, when fired, assumes a colour ranging from dull ochre to red. Terra-cotta objects are usually left unglazed and are often of a utilitarian kind, because of their cheapness, versatility, and durability. Small terra-cotta figures from 3000 BC have been found in Greece and others throughout the Roman Empire from the 4th century BC. The use of terra-cotta virtually died out when the Roman Empire collapsed, but it was revived in Italy and Germany in the 15th century.

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Glazed architectural terra-cotta is a ceramic masonry building material popular in the United States from the late 19th century until the 1930s, and still one of the most common building materials found in U.S. urban environments. It is the glazed version of architectural terra-cotta; the material in both its glazed and unglazed versions is sturdy and relatively inexpensive, and can be molded into richly ornamented detail. Glazed terra-cotta played a significant role in architectural styles such as the Chicago School and Beaux-Arts architecture.

The material, also known in Great Britain as faience and sometimes referred to as "architectural ceramics", was closely associated with the work of Cass Gilbert, Louis Sullivan, and Daniel H. Burnham, among other architects. Buildings incorporating glazed terra-cotta include the Woolworth Building in New York City and the Wrigley Building in Chicago. It is also used in the open-air Bridgemarket under the Manhattan side of the Queensboro Bridge.

Variations in the color and pattern of the glaze made it possible for buildings constructed with the material to look like they were finished with granite or limestone; this flexibility was part of the reason the material was so attractive to architects at the time.

Glazed architectural terra-cotta offered a modular, varied and relatively inexpensive approach to wall and floor construction. It was particularly adaptable to vigorous and rich ornamental detailing. Terra-cotta is an enriched molded clay brick or block. It was usually hollow cast in blocks which were open to the back, like boxes, with internal compartment-like stiffeners called webbing. Webbing substantially strengthened the load-bearing capacity of the hollow blocks without greatly increasing its weight. The blocks would then be finished with a glaze, with a clay wash or an aqueous solution of metal salts, before firing. Late 19th century advertising for the material promoted the durable, impervious and adaptable nature of glazed architectural terra-cotta. It could accommodate subtle nuances of modeling, texture and color. Compared to stone, it was easier to handle, quickly set and more affordable to use. The cost of molding the clay, glazing and firing the blocks, when compared to carving stone, represented a considerable savings, especially when casts were used in a modular fashion--that is, repeated over and over again. It never needed paint and periodic washings restored its original appearance.

In wide use, there were four major types of terra-cotta used:

1) Brownstone was the earliest type. A dark red or brown block which was not necessarily glazed. It was used as imitation sandstone, brick or real brownstone and associated with the architectural styles of Richard Upjohn, James Renwick, H. H. Richardson.

2) Fireproof was developed as a direct result of the growth of the high rise building in America. Cheap, light and fireproof, the rough-finished hollow blocks were ideally suited to span the I-beam members in floor, wall and ceiling construction. Certain varieties are still in production today.

3) Veneer was developed during the 1930's and is still used today. Unlike traditional architectural terra-cotta, ceramic veneer is not hollow cast. It is a veneer of glazed ceramic tile which is ribbed the back like bathroom tile and usually attached to a grid of metal ties which have been anchored to the building.

4) Glazed architectural terra-cotta was the most complex building material developed. The hollow units were hand cast in molds or carved in clay and heavily glazed, then fired. This is the terra-cotta associated with the architecture of Cass Gilbert, Louis Sullivan and Daniel H. Burnham.

Use in America

The American Terra Cotta Corporation, founded in 1881, operated for eighty-five years in the little town of Terra Cotta in the heart of Illinois dairy country (near Crystal Lake, Illinois), the company fabricated architectural terra cotta for more than 8,000 buildings throughout the U.S. and Canada. It was the last exclusive manufacturer of architectural terra cotta by the time it ceased production in 1966. From its fortuitous founding in time to rebuild the fire-ravished city of Chicago until its closing, it was the major producer of architectural glazed terra cotta on the North American continent.

Use of terra cotta by Chicago architect Albert Hecht

Use in Canada

Although glazed terra-cotta was much more common in the U.S., it was used in central Canada starting around 1900, on many of the area's first skyscrapers. The glazed terra-cotta used in central Canada was usually imported from the U.S. or England.

Use in Great Britain

From around 1890 the use of unglazed terra-cotta lost ground to the glazed version - faience, and glazed brick - which were comparatively easy to clean and were not blackened by city smoke.

See also

• Architectural terra-cotta
• Guastavino tile

Further reading

Brick - A World History, James W P Campbell & Will Pryce, 2003, ISBN 0-500-34195-8

External links and sources

• The Tile Heritage Foundation, "...a nonprofit charitable organization, ...dedicated to promoting an awareness and appreciation of ceramic surfaces in the United States".
• The Preservation of Historic Glazed Architectural Terra-Cotta, from a National Park Service website
• Ottawa's Former Bowles Lunch, a January 2002 article from the Heritage Ottawa website
• Renovation of Bridgemarket under the Queensboro Bridge, from the website of the architects involved in the project
• Gladding McBean Architectural terra cotta company
• Boston Valley Terra Cotta Architectural terra cotta company.
• Randalls Lost New York City, Photos of architectural terra cotta and gargoyles from demolished buildings.
• TerraGlas terra cotta composite company TerraGlas website with CAD drawings, historical replacement information and specifications.

References