The Secret of Coade Stone

The large lion statue that stands at the east end of Westminster Bridge, near the Houses of Parliament, holds a secret—it is made neither of stone nor of concrete but from a special mixture of ingredients whose recipe was lost to the world for more than a hundred years. The statue is close to two hundred years old, yet looks brand new with no visible signs of weathering on its surface. The fine details of its modelling still remain clear after centuries of exposure to the corrosive atmosphere of London. This remarkable artificial stone is known as Coade stone, named after Eleanor Coade, who owned the factory that made it. Coade stone was immensely popular during the 18th and the 19th centuries because it was practically indestructible and could be shaped into any kinds of ornamental objects, including friezes, arabesques, capitals and other decorative architectural items. Every leading architect of the time used it, and its examples can be found all over the world. Coade stone lion on Westminster Bridge, London. Photo: ddub3429/Shutterstock.com Coade stone looks and feels exactly like worked stone, but it isn’t stone at all. It is a type of ceramic called stoneware. Ceramic, as you know, is just baked clay, but depending on the type of clay and how intensely they are fired, the kiln will produce different types of material. Low temperature firing results in earthenware (terracotta, pottery, bricks etc.). These are fragile. Higher temperature causes vitrification of the clay and results in a much tougher material called porcelain. An even higher temperature is needed to produce stoneware. These are dense, impermeable, noncorrosive and resistant to scratching. At the time Eleanor Coade set up her “Coade's Artificial Stone Manufactory” in Lambeth, there were many businesses manufacturing artificial stone in England. Eleanor Coade, the daughter of a wool merchant, in all likelihood, knew next to nothing about making artificial stone.