By Vincenzo Burdi
Terracotta has been used throughout history for sculpture, pottery, and building material. In ancient times, clay sculptures were dried in the sun after being formed. Today, the material is placed within what is known as a kiln, essentially a furnace for clay. Compared to stonework, terracotta is far lighter, it can be reproduced with reusable mold-making techniques, and can be further glazed to produce objects with color and texture.
Variations in the color and pattern of the glaze make 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.
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.
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.
3) Veneer was developed during the 1930's and is still used today. 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.
Glazed architectural terra-cotta is a ceramic masonry building material popular in the United States from the late 19th century until the 1930s. It is 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.