Glazed architectural terra-cotta

Glazed architectural terra cotta is a ceramic masonry building material used as a decorative skin. It featured widely in the 'terracotta revival' from the 1880s until the 1930s. It was used in the UK, United States, Canada and Australia and is still one of the most common building materials found in U.S. urban environments. It is the glazed version of architectural terracotta; 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", in the USA 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. 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. It was created by Luca della Robbia (1400–1482), and was used in most of his works. Terra-cotta is an enriched molded clay brick or block. It was usually hollow cast in blocks which were open in the back, with internal stiffeners called webbing, substantially strengthening the hollow blocks with minimal weight increase. The blocks were 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 with stone, it was easier to handle, quickly set and lower cost. The cost of producing the blocks, when compared to carving stone, was a considerable saving, especially when casts were used in a modular fashion—that is, used repeatedly.