Cornwalls China Clay
China Clay is by far one of the purest forms of clay one can find and is composed of the mineral kaolinite which is typically formed when granite is changed by a process known as “hydrothermal metamorphism”. The terms “china clay” and “kaolin” are not very well defined and are sometimes used synonymously for an entire clay group and sometimes kaolin is used to refer to the types of clays found in the United States and china clay used for those that are imported. China Clay is the more “plastic” of the kaolin variety. The clay is used primarily in the ceramic industry chiefly fine porcelain as the clay is easily molded with a very fine texture and when fired is white. They are also used as filler in some papers. The clay deposit, in the United States, is generally found in Georgia, Pennsylvania and North Carolina. The clay is also found and mined in Cornwall, England and France.
In the early days of the industry it was, obviously, all the more concerned with locating and producing china clay for ceramics. The story of china clay, however, begins several thousands years ago and many, many miles away.
Everyone is familiar with “fine china” which is the pure white and expensive ceramic made by the Chinese. The name of the porcelain comes from the type of clay that it used. It was discovered thousands of years ago and ever since has been very well valued. There were many attempts made to find the material all over the world but that would not be the case. The few other deposits were found in some areas of Europe and only 3 places in the United States and that only occurred in the 18th century. The Europeans increased their search of deposits in England and when, finally, it was discovered they determined it was much a finer material than originally expected.
William Cookworthy, a Quaker apothecary-cumpotter, made the find in Cornwall in 1746 and experimented with it and in 1768 he applied for a patent for its use. He soon began making items in “Plymouth Porcelain Factory”, the company he formed. Before this time the pottery that was made in England was rough earthenware and stoneware.
The demand grew and grew as more pottery made use of porcelain. Because of this the pottery industry became successful. Many Potters owned the rights to mine the materials for themselves. By the middle of the nineteenth century the china clay that was being produced was being used as raw material for the paper industry.
Early on in the Twentieth century the industry was made up of seventy different producers of the clay. Each of these producers competed against each other in price and they had no regard for standard, marketing and barely made any investments whatsoever in the development of products. Production was over-used, wages low and the conditions in the mines were horrible.
By 1910, despite the over production and poor conditions, the production of china clay had risen to close to a million tons each year and the paper industry had nearly completely overtaken ceramics as the primary user of the material. 75% and more of the material was exported. North America and Europe were the primary markets. The china clay industry in Cornwall as well as Devon had a monopoly on the supply to the world market as the other producing sites were small and limited. English China Clays Limited was formed in 1919 and consisted of the three major producers in England. This made nearly half of the mineral produced under one company.