Details

The monument, which falls into two areas of protection, includes part of a china clay works situated in the Ruddle Valley by the St Austell River at Carthew. The surviving clay works includes a water engine for pumping slurry from the clay pits by vertical rods and a balance bob connected to a working over-shot water wheel, a second waterwheel which worked flat rods to the clay pit, an engine house, a series of mica and sand drags, settling tanks, the blueing house, workers shelter or crib hut, the linhay or drying area and the coal fired furnace. Most of the structures are complete and the machinery in working order and form the core of exhibits in a museum. Further remains to the south including three oval settling tanks survive but are not on display.
The Wheal Martyn works were established in the 1820's by Elias Martyn and were one of the major producers of china clay until his death in 1872. After a period of partial closure, the works were re-opened by John Lovering who developed the works and introduced new techniques to maximise production. In 1931 the clay pit closed following a slump in demand but the dry remained in use working lower grade clay from other pits in the area and finally closed in 1966. By 1971 the works were again operational and by 1975 much of the processing facilities were opened to the public as a museum. The surviving equipment generally dates to the period when Lovering took over production.

Sources: HER:-
PastScape Monument No:-431205

Source: Historic England

Reasons for Scheduling

The china clay industry originally developed in conjunction with the production of fine ceramics, chiefly porcelain, which had been known to the Chinese for centuries but were not produced elsewhere. In 1746 William Cookworthy discovered kaolin in Cornwall of a finer quality than anywhere in Europe. Combined with the locally available china stone which was mixed with the kaolin to form a paste it became possible to produce fine quality ceramics. The kaolin was of immense significance to other industries including paper, paint, pharmaceuticals and for agricultural purposes to name a few of many. In the early 20th century there were approximately seventy individual kaolin producers and in common with many industries investment was poor and over production was high. By 1910 the major markets were North America and Europe and much of the product was used by the paper industry. At this time the china clay producers in Devon and Cornwall had a near monopoly within the world market. After the First World War the three major producers amalgamated and dominated the modern industry. Kaolin is extracted from the granite in which it is found using water. Originally washed off by channelled water at the surface the process became more mechanised with time until high pressure jets called monitors were employed. The clay was carried in suspension and was pumped from the clay extraction quarries or 'pits' via refining channels. The waste micas and sands in the resultant slurry were trapped en route. The material then entered settling tanks where it remained for up to three months of sedimentation. Once partially solidified the clay was transferred to the 'dry' or kilns where it was spread over heated pantiles to dry thoroughly before being cut into blocks. The economic, social and political importance of this industry continues, and the part of a china clay works known as Wheal Martyn is important because it graphically demonstrates and preserves the earlier innovations of the industry before it became the highly mechanised process of today. The china clay quarry is still in use and produces about 2000 tons of china clay per week, which is approximately the same quantity Elias Martyn generated in a year.

Source: Historic England