Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/666

Rh 642 P O T T E K Y Worces ter porcelain. the o vner of tlie place. He soon realized a large fortune, though to some extent at the expense of the credit and high reputation for excellence of work which had been gained and kept up by the various members of the Dues- bury family. He gained a great deal of money by selling oft the stock, accumulated during many years, of slightly defective pieces of porcelain, which the Duesbury family would not allow to go into the market. 1 Worcester Porcelain. The china- works at Worcester Avere founded by a very remarkable man Dr Wall, who a pp ears ^o have possessed unusual skill as a physician, artist, and chemist. After some years spent in attempts to discover a fine artificial porcelain, he, in conjunction with other practical men and capitalists, started the Worces ter Porcelain Company in 1751. The early productions of this factory are very artistic ; they are chiefly copies of the fine Nanking porcelain, painted under -glaze in blues only, with very boldly decorative designs. Old Japanese ware was also successfully imitated. After that the most ambitious pieces of Worcester porcelain were mostly dull reproductions of the elaborately painted wares of Sevres and Chelsea. Transfer printing was first used at Worcester for designs on china in 1756, though it had been invented and employed some years earlier for the decoration of the Battersea enamelled copper. This process was no less injurious at Worcester than elsewhere to the artistic value of the paintings. Dr Wall died in 1776, and after that the porcelain -works passed through various hands. A great impetus was given to its success by George III., who visited the factory in 1788 and granted it the title of &quot;The Royal Porcelain Works.&quot; The earliest marks are a &quot; W &quot; or a crescent ; others used are crossed arrows or varieties of sham Chinese marks (see No. 40). 2 The manufacture of china at Worcester is still continued with great ac tivity ; the fineness of the paste and the skilful processes employed leave nothing to be desired. Un fortunately the old fault of a too realistically pictorial style of painted decoration still prevails, and an immense amount of artistic skill and patient labour is practically wasted in producing minute but not truly decorative work. Some of the modern Worcester copies of Eastern porcelain and enamels are very delicate and beautiful, and the cameo-like method of pate sur pdte de coration is practised with great skill and often good effect. Bristol Bristol porcelain is of interest as being the first hard P rcelam&amp;gt; natural porcelain made in England. As early as 1766 attempts were made by Richard Champion to make an artificial paste, with the help of the American &quot; unaker &quot; or kaolinic clay, which was being used successfully at Bow, but no results of any importance seem to have followed his experiments. The successful production of Bristol porcelain was due to the discovery in Cornwall of large beds of kaolinic &quot; growan &quot; stone or &quot; china &quot; stone, first brought into use by William Cookworthy, a Plymouth potter. This discovery and the succeeding one of similar beds in Devonshire were of great commercial importance to England, and the beds have ever since produced enor mous quantities of material for the manufacture of fine hard porcelain both in England and abroad. This china stone (see Cock, Treatise on China Clay, 1880) is not a pure kaolinic clay like that found in China, but is simply a granitic rock, partially decomposed, and soft and friable, but still retaining both quartz and mica in addition to the felspar, which i the essential base of kaolin. In China the processes of nature navejiarried the decomposition and sorting of the different com- 1 See Haslem, Old Derby China Factory, 1876. 2 For fuller information, see Binns, Pottinrj in Worcester, 1865. Potter s marks. No. 40. ponent parts of granite to a further stage. There the decomposed felspar has, by the action of rain and running streams, been deposited in an almost pure and finely-divided state in beds by itself, almost free from quartz and Makes of mica. In using the Cornish china stone, therefore, various natural processes have to be artificially performed before the paste is sufficiently white and pure for use ; but when this is done it is little if any inferior to the Chinese kaolin. The stone when dug out is white with grey specks, and is so friable as to be easily reduced to powder between mill stones. It is agitated with water, and run through a series of settling troughs ; thus the lighter flakes of mica, which are very injurious to the paste, are washed away, and the pure felspathic kaolin is deposited free from impurities. Free silica is added in a fixed proportion ; it is usually obtained from flints, first calcined and then finely ground to powder, which are an important ingredient in the composition of both fine pottery and porcelain. The Jerniyn Street Museum has a complete collection of all the materials used in china manufacture. William Cookworthy at once recognized the value of his discovery, and set up china-works both at Plymouth and at Bristol. No. 41 shows the mark of the Plymouth porce lain, and No. 42 those that were used at Bristol. In 1774 he sold the Bristol fac- S tory to Richard Cham- ^ pion, still retaining a U large royalty on the china stone. Champion signed his ware with No. 43. The produc- &quot;NO. 41. No~42. No. 43. No. 44. tionof Bristol porcelain Potters marks, continued till 1781, when the works were sold to a Staffordshire company, and the manufacture of hard porce lain was no longer carried on there. Though fine in paste and unusually transparent, the Bristol porcelain has no special artistic merits. As with most other English wares, the best in colour and design are copies, with more or less adaptation from Eastern china ; some of them are very large and magnificent. The figures and flower-reliefs in biscuit porcelain are also delicate, and often cleverly modelled, with wonderful realism. Some fine blue and white china was produced towards Oth the end of the last century at Lowestoft, and at Liverpool cllil as early as 1756 ; and many other china-works were estab-^ lished in various parts of England. In the beginning of the present century Swansea and Nantgarw in South Wales produced porcelain which was highly esteemed ; but the delicate shades of difference in the paste, glazes, and styles of decoration of these numerous varieties of British porce lain are not such as can be described in a few words ; nothing but careful examination of the wares themselves will enable the student to distinguish between the produc tions of the different manufactories. Swansea ware bears various marks, of which No. 44 is one example. Modem Methods of Manufacture. The methods and materials Ma now employed at Sevres in the production of porcelain are in all fac essential points much the same as those practised elsewhere (see above). The chief centre in England of the manufacture of pottery or non-translucent earthenware is in Staffordshire, near the borders of Cheshire, where a large district devoted to this industry goes by the name of &quot; The Potteries. &quot; Worcester, Lambeth, and many other places in England also turn out annually large quantities of pottery. The processes employed may be divided under the following heads : (1) choice and mixture of clays ; (2) washing and grinding the materials ; (3) throwing on the wheel and moulding ; (4) kilns and methods of firing ; (5) glazes ; (6) pigments and methods of decoration. 1. Choice and Mixture of Clays. The extensive beds of fine Dorset Mi re or Poole clay supply the chief ingredient in the manufacture of of f 8 - English pottery. This is too fat a clay to be used alone, and is therefore mixed with a certain proportion of free silica to prevent it from twisting or cracking in the kiln. Another ingredient is added to the mixture for the finer wares, namely, the Cornish or Devonian china stone, a kaolinic substance used in the manufacture of porcelain (see above), which makes the paste finer in texture, whiter, harder, and less brittle. These three substances are mixed in various proportions. The following makes a fine cream-coloured ware, Dorset clay 56 to 66 parts, silica (flint) 14 to 20, china stone 17 to 30 parts.