but it is fired to a lower temperature (around 800 °C as opposed to 1,100 to 1,200 °C) and glazed with lead to form a cream-coloured earthenware. The white clays ensured a fine body and the addition of flint improved its resistance to thermal shock during firing, whilst flint added to the glaze helped prevent crazing. Development Creamware was first produced some time before 1740. Originally lead powder or galena, mixed with a certain amount of ground calcined flint, was dusted on the ware, which was then given its one and only firing. This early method was unsatisfactory because lead powder produced poisoning among the potters and the grinding of flint stones caused a form of silicosis known as potter's rot. Around 1740 a fluid glaze in which the ingredients were mixed and ground in water was invented, possibly by Enoch Booth of Tunstall, Staffordshire, according to one early historian, although this is disputed.Simeon Shaw, History of the Staffordshire Potteries, Hanley, Printed for the author (1829), p 18 The method involved first firing the ware to a biscuit state, and then glazing and re-firing it. Foremost of the pioneers of creamware in the Staffordshire Potteries was Thomas Whieldon. Although he has become popularly associated almost exclusively with tortoiseshell creamware, in fact he produced a wide variety of creamware. He first mentions ‘Cream Colour’ in 1749. The young Josiah Wedgwood was in partnership with Thomas Whieldon from 1754 to 1759 and after Wedgwood had left to set up independently at Ivy House, he immediately directed his efforts to the development of creamware. Wedgwood rebelled against the use of coloured glazes, declaring as early as 1766 that he was clearing his warehouse of coloured ware as he was ‘heartily sick of the commodity’. Wedgwood improved creamware by introducing china-clay into both the body and glaze and so was able to produce creamware of a much paler colour, lighter and stronger and more delicately worked, perfecting the ware by about 1770. His superior creamware, known as ‘Queen's ware’, was supplied to Queen Charlotte and Catherine the Great and later became hugely popular. There were few changes to creamware after about 1770 and the Wedgwood formula was gradually adopted by most manufacturers. Pearlware One important ware of note however is pearlware, of which there was an increase around 1779. Pearlware is distinct from creamware in having a blue-tinged glaze produced by the use of