Made from a mixture of clay, feldspar and limestone, Seger Cones were used by North Staffordshire’s pottery industry to indicate the temperature inside coal fired bottle ovens and kilns.
When ware was being fired a set of four cones was placed with it in the kiln or the oven.Each cone was made so that it would bend at a specific temperature. From time to time during the firing, the kiln man (pronounced kilman) would view the cones through a spy hole in the side of the oven or the door of the kiln. As the temperature rose, the cones began to bend. After two, three or four days, the cones showed that the temperature was hot enough to have fired the ware. The coal fires were allowed to die and the oven was left to cool before the ware was taken out.
Seger Cones were invented in 1886 by German ceramic technologist Hermann Seger while working at the Royal Porcelain Works in Berlin.
Before the First World War (1914-18) all the Seger Cones used in the Potteries were imported from Germany. When war broke out on August 4th, 1914 all trade with Germany ceased and the pottery industry faced a major crisis. Realising the industry could not survive without Seger Cones, the Governors of the Central School of Science and Technology (which became the North Staffordshire Technical College in 1926) held an emergency meeting. They decided to manufacture the cones at the school on a commercial basis. A science laboratory was turned into a workshop and Dr. Joseph Mellor the head of the school’s ceramics department was put in charge of production.
A workman, Harry Tams, from Longton was employed to make the cones. He was paid 25 shillings (£1.25) a week.
Manufactured under Joseph’s supervision, the cones, called Staffordshire Cones, were stamped with the de Stafford knot. The venture was so successful that Joseph’s salary was raised by a £100 per annum. In February, 1915, two boys, each of whom was paid five shillings (25p) a week, were employed to help Harry in the workshop. Demand for cones continued to increase and two more boys were taken on.
The governors estimated that the income from sales would be about £200 a year and towards the end of 1915 an order for 200,000 cones was received.
(Copyright Betty Cooper/David Martin – The Phoenix Trust 2010)