Nineteenth Century Salt Making – Developments in Salt Making Technology
After Furnival’s departure, the development of “patent pans” was continued at all three works and no doubt elsewhere. By the end of the century the Salt Union were still operating “machine pans” based essentially on the principle of the patent pan. Such pans were still working at Stoke Prior in the 1920’s.
Most salt makers however continued to use traditional open pan methods and during the 19th century worked to a standard pattern based on two pan types, the fine pan and the common pan. Both types were a standard 24 to 25 feet width to allow the 12 foot handled salt rakes to draw the salt from the centre of the pan.
Fine pans were about 40 feet in length and worked with fast fires so that the heat of the flue gases rapidly boiled the brine and also heated the adjoining hothouses where the salt made into lumps was dried before being crushed and milled to form a fine crystalline drysalt suitable for dairy and domestic uses. Common pans were at least double the length of the fine pan. They were without an adjacent hothouse so that the flue gases only heated the pan before reaching the chimney. Often three common pans would share one chimney. The common pan fires were banked with slack so that the pans worked at simmering temperatures and yielded large crystals. Industrial salt for the alkali makers was drawn from the pans after one or two days but longer periods yielded larger crystals and salt for tanneries or fishery use and could have been a one, two or three-weeks. The crystals were drawn from the pan and heaped to drain along the sides of the pan. The drained salt was then moved by handcart either to the warehouse or direct to a boat or railway wagon.
There were various modifications of the process. Some works in the 1860 to 1880 period were using steam heated wooden pans which at a temperature of 35-40 degrees centigrade yielded fishery salt after about 6 weeks operation. By the early 20th century the Salt Union at the Mersey Brine and Salt Works at Weston Point were producing fishery salt in common pans heated by Mond Producer Gas.
Albert F Calvert in his bulky “Salt in Cheshire” [Spon 1915] makes what are suspiciously exaggerated claims for the Hodgkinson Patent process which was a sophisticated arrangement in which steam and flue gases from enclosed boiling pans was used to heat other vessels and finally common pans. The process had been on trial by the Salt Union at their Northwich works but rejected. Calvert in his book failed to mention that he was the holder of the patent rights and hence had a special interest in promoting the process. Following the Salt Union’s rejection of the process Calvert acquired the lease of the Lawton Salt Works and established the Commercial Salt Company which took over the Hodgkinson plant. This was transported from Northwich to Lawton and re-erected but it never operated successfully and was eventually dismantled.
Calvert’s involvement with the Cheshire salt industry was for along time something of a mystery and only in recent years with the publication in Australia of a biography of Albert F Calvert [“Calvert’s Golden West”, Geoff Blackburn, Western Australia 1997] was it fully realised that his fortune had been made in the gold fields of Western Australia where he had followed in the footsteps of a famous grandfather John F Calvert the author in 1853 of a still definitive work; “The gold rocks of Great Britain and Ireland and the gold regions of the world”.[Chapman and Hall, London, 1853].Another innovative method of salt making of the early 20th century was the Tee Process patented by Harry Tee in 1903. The process made usable salt directly from rock salt by fusion of the crushed rock and the settling of impurities in the molten salt which was then decanted into lump forming moulds. The lumps were crushed and graded into fishery and table salts. The Tee Salt Manufacturing Process was working in 1910 at Carrickfergus in Northern Ireland by the Salt Mines Syndicate and was still receiving optimistic press reviews in 1913. But it nevertheless failed to compete with the open pan process and had a short life.