889 POTTERY AND PORCELAIN, MANUFACTURE OF. 



POTTERY AND PORCELAIN, MANUFACTURE OF. 690 



letters, monograms, dates, and coats of arms. Thus, Savona has the 

 arms of the town ; Nevers, N. ; Rouen, a fleur-de-lis ; B. stands for 

 Bernard Palissy ; Hochst has a wheel ; Cologne, an anchor ; Delft, 

 occasionally a sword ; Wedgwood and his successors stamped their 

 names ; old Dresden has the monogram A. R., King Augustus, K. P. M., 

 " the Royal Porcelain Manufactory," and crossed swords ; Venice, the 

 imperial arms ; Furstenburg, an F. ; Frankenthal, the lion and crown ; 

 Nymphenburg, the arms of Bavaria ; Ludwigsburg, a ducal crown and 

 C. C. ; Berlin, a globe and cross ; Fulda, F. crowned ; St. Petersburg, a 

 K. crowned ; the Hague, a stork ; Copenhagen, waves ; Nyon, troute ; 

 Chelsea, anchors ; Derby, a crowned D ; Plymouth, the astrological 

 sign for Jupiter ; Worcester, W. and other marks ; Swansea, a trident. 

 Sevres has several marks, a sun under Louis XIV., a crowned eagle 

 under Napoleon, a comet ; the other French potteries have monograms 

 and marks. The Chinese marks have the name of the maker, or date 

 when made, generally in red or blue, in a square label in the seal or 

 court characters, imitating the impression of the seals or stamps they 

 affix to their documents and books. 



The application of the fine arte to the embellishment of porcelain, 

 and the refinements of luxury, have vastly increased the value of modern 

 porcelain. For a long time hard porcelain was the monopoly of princes, 

 and the expense of producing specimens with charming colours and 

 elegant designs was very great ; but the desire of possessing beautiful 

 and rare specimens by the rich has greatly increased then- value : for 

 example, the majolica salt-cellars have realised at public sales from 10 

 guineas to 642. ; the Gubbio plates from 112. to 212. ; those of the artist 

 Xanto 802., and vases of larger size 2202. ; a Palissy candlestick, 842. The 

 ware of La Doccia has augmented its price 2000 per cent., and a small 

 cup of this ware is worth from 302. to 402. Chelsea vases of any size, 

 painted with religious or historical subjects, obtain from 1002. to 150/., 

 and small cups of this ware 252. to 302. Nor has the reputation of 

 Chinese crackle declined, and even mandarins might pause at the 

 prices given ; 602. and 702. being paid for sea-green or turquoise 

 blue vases. Green crackle has found amateurs to purchase at 1312.; 

 and a few flat jars, surmounted by kelins, or mystical stags, 235 

 guineas. Last, though not least, two jars have been the subject of 

 a suit in Chancery. Under such circumstances, the acquisition of 

 instructive collections transcends the power of princes or the prudence 

 of governments. 



(Brongniart, Traitt des Arts Ctramiques, 8vo, Paris, 1844; Birch, 

 History of Ancient Pottery, 8vo, Lond., 1858 ; Marryat, History of 

 Pottery and Porcelain *&vo, Lond., 1857.) 



POTTERY AND PORCELAIN, MANUFACTURE OF. The object 

 of the present article is to add a few further observations to the manu- 

 facturing details given under EARTHENWARE; and to apply those 

 details to the two kinds of ware which form the extremes of the 

 series, namely, fine or porcelain, and coarse or pottery : earthenware 

 occupying a medium position between the two. 



In the beginning of the last century, it was ascertained by experi- 

 ment that the earths alone are infusible, but that when silex is com- 

 bined with aluminous earth, and subjected to a strong fire, it unites 

 chemically with the clay, as an acid unites with a base ; and that when 

 a third earth, having alkaline properties, at) lime, magnesia, or barytes, 

 is added, a more complete change is effected, and a vitrified body is pro- 

 duced, resembling in density and fracture many natural gems. When 

 the earthy materials are free from metallic matter, a perfect porcelain 

 is thus produced. It was found that seven parts of silex, six parts of 

 aluminous earth, and two parts of an alkaline earth, would produce 

 such a body. On this principle the Germans and French founded their 

 porcelain manufactures. In England the enterprising spirit of Wedgwood 

 wrought a complete revolution in the art ; and by bold experiments, 

 guided by his knowledge of mineralogy and chemistry, he laid the sure 

 foundation for all those improvements which have raised the fictile 

 manufactures of this country to so high a level. 



The materials are reduced to the consistence of cream, in which state 

 they are called slips (slops) ; this fluidity is necessary to ensure the 

 perfect mixture of all the ingredients, and their mutual chemical action 

 in the fire. The basis of the composition is a clay from the plastic-clay 

 formation in Devonshire or Dorsetshire, to which is added ground flint, 

 which gives whiteness and solidity to the goods. For the better kinds, 

 a portion of China-clay, or decomposed felspar from Cornwall, is added, 

 together with a small quantity of ground white granite. The pro- 

 ceases are conducted as described in EARTHENWARE, until a smooth 

 and homogeneous mass of plaotic clay is produced. 



It may be well here to give the proportions of ingredients for various 

 kinds of ware or bodies, derived from the actual practice in Stafford 

 shire : 



Cream-colour or Printed Ware. 



Dorset clay . . . . 66 or 60 or 68 



China clay .... 27 18 17 



Flint 14 20 17 



Cornish granite ... 3 2 



Dralj-colnured Ware is made of the fine gray marl found between the 

 coal strata, which burns to a cane-colour in the oven ; or a white body 

 as above, is stained with oxide of nickel, which gives it a greenish drab 

 tint : or with oxide of manganese. 



ARTS ASD SCI. DIV. VOL. VI. 



Drab body. Cane marl . 

 Dorset clay . 

 Cornish granite 

 Oxide of nickel 

 Manganese . 



32 or or 56 or 23 



22 43 20 46 



45 50 24 25 



1 . 7 



3 



The granite in the above bodies gives great density and a very close 

 linty fracture. 



Sroicn or Chocolate bodies are made with a basis of the red ochreous 

 clay, obtained from the red-marl formation above the coal strata. A 

 jreat variety of tints may be obtained by judicious combinations of 

 oxides of iron, as umber, calcined copperas, bole, &c. 



Jirown. Red clay 



Dorset clay 

 Flint . 

 Manganese 



83 or 60 

 13 30 



2 10 



2 



Egyptian Black, for tea-pots, ink-standa, &e., is made in the same 

 way, but with a larger portion of the oxides of iron and nicinganese. 



laxic. Red clay 



Dorset clay 



Protoxide of iron 



45 or 34 



36 42 



13 12 



6 12 



Slue bodies are prtduced by the mixture of a small quantity of oxide 

 of cobalt with a fine white body ; when made of vitrescent materials, 

 so as to give a gem-like surface without glazing, it is termed jasper. 

 This beautiful article is well known by the splendid productions of 

 Mr. Wedgwood. 



Jasper bodiet. 



Sulphate of barytes 

 China clay 

 Dorset clay . 

 Flint 

 Gypsum 



48 or Carbonate of barytes . 34 



16 China clay . . . 15 



24 Dorset clay . . .15 



10 Cornish granite . . 33 



2 White lead . 3 



These mixtures give a fine white body for ornaments, which may be 

 stained blue by the addition of one per cent, or less of oxide of cobalt, 

 according to the strength of tint required ; or a green jasper may be 

 produced by staining with protoxide of chrome. 



Turquoise bodies. A body called turquoise has been manufactured 

 to a great extent. It is nothing more than a good white body, stained 

 with a mixture of oxide of cobalt, combined with a large proportion of 

 oxide of zinc ; when glazed, it haj the peculiar milky tint of the gem 

 after which it has been named. 



In this manner, by a proper combination of metallic oxides, either 

 as existing in earthy materials, or prepared from their metals, an 

 infinite variety of coloured bodies may be produced. They are usually 

 prepared on slip-kilns of small dimensions, . the bottoms of which are 

 covered with a layer of plaster of paris, if used for the finer colours. 



Referring to EARTHENWARE for an account of the manner of fashion- 

 ing circular vessels on the potter's or throwing wheel ; turning them 

 to the proper thickness, and working mouldings, &c. ; fixing on handles 

 and spouts ; and making the peculiar variety called dipped ware : we 

 shall odd a little to the details there given concerning ornamented ware 

 and fat ware. 



Thrown and turned goods are sometimes ornamented with figures in 

 relief, which are made out of flat moulds by children, and fixed upon 

 the ware by workmen, who, having carefully adjusted each figure to 

 its place, run a little water under it with a camel-hair pencil, which 

 unites it to the surface. Goods of an oval or angular shape, which 

 cannot be turned, are made by pressing clay into plaster moulds, which 

 give the outside form to the vessels. For this purpose the mould is 

 made in two parts, and each is separately filled by laying in a cake of 

 clay that has been beaten out to the proper thickness on a wet 

 plaster-block ; it is pressed into the mould by repeated blows from a 

 ball of wet sponge, then squeezed into all the angular parts with the 

 fingers, and smoothed with sponge, wet leather, and horn. When both 

 sides of the moulds are thus lined with clay, they are joined together ; 

 and the workman lays a roll of clay along the inside of the joining, 

 which he works down until the whole is smooth and solid. The mould 

 is then carried into a stove-room ; and when it has absorbed the 

 moisture, so as to release the clay, the work is carefully taken out, 

 and the empty mould returned to the stove previous to being filled 

 again. The seam which remains on the outside of the vessel is 

 removed by scraping and burnishing with wet horn ; the handles and 

 other appendages are then attached. This branch of the trade is 

 called tiollow-icare pressing or squeezing. Flat-ware pressing is per- 

 formed by giving the shape to the goods by moulds which fit the 

 inside of the vessel ; plates, dishes, saucers, cups, and hand-basins are 

 made on this principle by the English potter, with a dexterity which 

 must be seen to be understood, and which excites the surprise of 

 foreigners more than any other branch. The workman stands at a 

 bench provided with a whirling-table similar to the thrower's, but 

 which has its motion given by a horizontal pulley or jigger, turned 

 by his young assistant. Close to his left hand is a batting-block 

 of wet plaster, and the mass of well-beaten clay from which he is 



Y T 



