622 POTTERY 



The impression above the glaze is done by quite a different process, which dispenses 

 with the use of the press. A quantity of fine clean glue is melted and poured hot upon 

 a large flat dish, so as to form a layer about a quarter of an inch thick, and of the 

 consistence of jelly. When cold it is divided into cakes of the size of the copper-plates 

 it is intended to cover. 



The operative (a woman) rubs the engraved copper-plate gently over with linseed 

 oil boiled thick, immediately after which she applies the cake of glue, which she 

 presses down with a silk dossil filled with bran. The cake licks up all the oil out of 

 the engraved lines ; it is then cautiously lifted off, and transferred to the surface of 

 the glazed ware which it is intended to print. The glue-cake being removed, the 

 enamel surface must be rubbed with a little cotton, whereby the metallic colours are 

 attached only on the lines charged with oil : the piece is then heated under the muffle. 

 The same cake of glue may serve for several impressions. 



Ornaments and Colouring. Common earthenware is coloured by means of two kinds 

 of apparatus : the one called the blowing-pot, the other the warming-pot. The 

 ornaments made in relief in France are made hollow (intaglio) in England, by means 

 of a mould engraved in relief, which is passed over the article. The impression which 

 it produces is filled with a thick clay-paste, which the workman throws on with the 

 blowing-pot. This is a vessel like a tea-pot, having a spout, but it is hermetically 

 sealed at top with a clay plug, after being filled with the pasty liquor. The workman 

 by blowing in at the spout, causes the liquor to fly out through a quill pipe which goes 

 down through the clay pipe into the liquor. The jet is made to play upon the piece 

 while it is being turned upon the lathe ; so that the hollows previously made in it by 

 the mould or stamp are filled with a paste of a colour different from that of the body. 

 When the piece has acquired sufficient firmness to bear working, the excess of the 

 paste is removed by an instrument called a tournason, till the ornamental figure 

 produced by the stamp be laid bare ; in which case merely the colour appears at the 

 bottom of the impression. By passing in this manner several layers of clay-liquor of 

 different colours over each other with the blowing-pot, net-work and decorations of 

 different colours and shades are very rapidly produced. 



The serpentine or snake pots, established on the same principle, are made of tin plate 

 in three compartments, each containing a different colour. These open at the top of 

 the vessel in a common orifice, terminated by small quill tubes. On inclining the 

 vessel, the three colours flow out at once in the same proportion at the one orifice, and 

 are let fall upon the piece while it is being slowly turned upon the lathe, whereby 

 curious serpent-like ornaments may be readily obtained. The clay-liquor ought to 

 be in keeping with the stoneware-paste. The blues succeed best when the ornaments 

 are made with the finer pottery mixtures given above. 



White and yellow figures upon dark-coloured grounds are a good deal employed. 

 To produce yellow impressions upon brown stoneware, ochre is ground up with a 

 small quantity of antimony. The flux consists of flint glass and flints in equal weights. 

 The composition for white designs is made by grinding silex up with that flux, and 

 printing it on as for blue colours, upon brown or other coloured stoneware, which 

 shows off the light hues. 



Metallic Lustres applied to Stoneware. The metallic lustre being applied only to the 

 outer surface of vessels, can have no bad effect on health, whatever substances be 

 employed for the purpose ; and as the glaze intended to receive it is sufficiently fusible, 

 from the quantity of lead it contains, there is no need of adding a flux to the metallic 

 coating. The glaze is in this case composed of 60 parts of litharge, 36 of felspar, and 

 15 of flints. 



The silver and platina lustres are usually laid upon a white ground, while those of 

 gold and copper, on account of their transparency, succeed only upon a coloured 

 ground. The dark-coloured earthenware is, however, preferable, as it shows off the 

 colours to most advantage ; and thus the shades may be varied by varying the colours 

 of the ornamental figures applied by the blowing-pot. 



The gold and platina lustre is almost always applied to a paste body made on 

 purpose, and coated with the above-described lead-glaze. This paste is brown, and 

 consists of 4 parts of clay, 4 parts of flints, an equal quantity of kaolin (china-clay), 

 and 6 parts of felspar. To make brown figures in relief upon a body of white paste, 

 a liquor is mixed up with this paste, which ought to weigh 26 ounces per pint, in 

 order to unite well with the other paste, and not to exfoliate after it is baked. 



Preparation of Gold Lustre. Dissolve first in the cold, and then with heat, 48 grains 

 of fine gold in 288 grains of aqua regia, composed of 1 ounce of nitric acid and 3 

 ounces of muriatic acid ; add to that solution 4$ grains of grain tin, bit by bit; and 

 then pour some of that compound solution into 20 grains of balsam of sulphur diluted 

 with 10 grains of oil of turpentine. The balsam of sulphur is prepared by heating 

 a pint of linseed oil and 2 ounces of flowers of sulphur, stirring them continually till 



