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.

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. On the contrary, she sold linen. But towards the end of the 1760s, she had the fortune of meeting one Daniel Pincot, who was already into the business of making artificial stone but was having difficulty keeping up with the finances. Eleanor Coade had the money and Daniel Pincot had the formula, and together they opened a factory on the south side of Thames where Waterloo Station stands today and began producing an unusually high-grade material. Coade originally named her stone Lythodipyra, which was Greek for “twice-fired stone”, before rebranding it to the punchier “Coade stone.” Within two years, Eleanor Coade had fired Daniel Pincot and nothing more is known about him.

Coade Stone Factory yard at Narrow Wall

An engraving of the Coade Stone Factory yard at Narrow Wall, Lambeth, London, in about 1800.

Eleanor Coade ran the business very successfully for fifty years until her death, which was very rare for a woman in the Georgian era. Materials from her factory was dispatched across Georgian Britain and beyond, and was used by many brilliant sculptors and architects of the day, including Robert Adam, James Wyatt, Samuel Wyatt, Sir William Chambers, John Nash, and John Soane. The crowning achievement of her career was gaining the royal appointment to both George III and the Prince Regent. Her stoneware was used for St George's Chapel, Windsor; The Royal Pavilion, Brighton; Carlton House, London; the Royal Naval College, Greenwich; and refurbishment of Buckingham Palace.

Eleanor Coade died in 1821. Her stone remained in use for another two decades before it was replaced by another marvelous invention—Portland cement.

There is an enduring myth that the secret of Coade stone died with Eleanor Coade. But this is not true. The formula for Coade stone was well known by the middle of the 19th century, and a number of manufacturers were using the recipe. This was possible because neither Pincot nor the Coades sought for a patent.

“That Coade stone was a single, patented formula is perhaps the most persistent myth,” writes Caroline Stanford. “The sheer range of size in Coade wares rendered a single formulation impossible: the proprietorial secret, if there was one, lay in the consummate skills of the craftsmen who mixed the clay and the fireman who tended the kiln.”

Nelson's Pediment Old Royal Naval College, Greenwich

Lord Nelson's Pediment in the King William Courtyard of the Old Royal Naval College, Greenwich, was regarded by the Coade workers as the finest of all their work. Photo: Brian Hancill/Flickr

Indeed, the manufacturing of Coade objects was a very time consuming process and required highly skilled labour. First, a model of the figure was made from clay to a size about 10 percent larger than required to allow for shrinkage during firing. A plaster mould was then taken from this model, usually in several sections that could be removed and reassembled. The Coade clay mixture was prepared and pressed into the mould by hand. Many old Coade stone pieces still carry fingerprints of Coade’s workers on the inside. Once the clay mixture hardened, the plaster mould was removed and the model was fired in the kiln for several days. This was the most critical stage of the process. Often the kilnsman stayed awake all night working the fire to keep the temperature constant. He didn’t always get it right—sometimes the iron rods corroded and cracks developed. These batches were rejected by Eleanor Coade who strived to maintain the highest standards of quality control. But most of the time, the Coade stones came out of the kiln in supreme.

Coade stone owns its success, to a large extent, to the entrepreneurial leadership of the woman who promoted it. Eleanor Coade forged highly productive relationships with some of the most respected architects and designers of the time, and through them had access to some of the wealthiest clients in Britain. She held exhibitions for her products at the Society of Artists in the 1770s and in 1799 opened a permanent exhibition gallery on the south side of Westminster Bridge. She placed frequent advertisements in the newspapers, and made sure that the best of the manufactory’s works were exhibited at the Royal Academy. Her designs were exhaustive. The 1784 catalogue, for instance, contained no fewer than 788 designs. Often the pieces could be customized according to her clients’ wishes.

Eleanor Coade never married. When she died in 1821, at the age of 88, she left much of her fortune to charity schools and clergymen.

Father Thames, a Coade stone sculpture Ham House, Richmond