Eleanor Coade - artist in artificial stone
Coade Stone: the process
For the best part of 50 years the Coade factory prided itself on its high standards, providing materials that fitted a wide range of uses and styles. The key to this success was the stone itself. Its recipe - tried and experimented with for years - was gradually perfected.
It was believed in the 19th and early 20th centuries that the formula had been lost with Eleanor at her death in 1821. However, it has been shown that Coade stone continued to be used for at least a decade after her death, most notably at Buckingham Palace (Kelly 1990, 55). Research at the British Museum during the 1990s confirmed this when the recipe was determined for the first time in over a century.
Most modern artificial stone is a form of concrete, where materials are hardened by chemical action without the use of heat. Coade stone was a form of ceramic, which is very different, as the final product involves subjecting the constituent materials to a considerable period in a kiln. With a low shrinkage rate during the firing process and a shiny, vitrified surface, the stone developed at the Coade factory was very strong and weather resistant (Kelly 1990, 56).
There were a number of steps in the production process of a Coade stone feature. First, a model of the proposed piece was built at a scale of 13 inches to the foot in modelling clay. Next, a plaster mould was made from the model and finally, the Coade clay was pressed into the mound and fired.
For very complicated pieces, a number of moulds were made up and the component pieces brought together by a skilled sculptor or ‘repairer'. The joins of the moulds are rarely seen on Coade pieces, as the marks left behind were removed through a process of ‘fettling' and ‘towing' (Kelly 1990, 61).
Once neatened and dried, the stone was fired for four days and nights continuously, under the constant watch of a fireman, who relied on his own judgement in maintaining the correct temperature. The finished article was then ready to be shipped.