POTTERY G25 



ware with a pencil, and afterwards levelled, or as it is technically termed ' bossed,' 

 until the surface is perfectly uniform ; as the deposit of more oil on one part than 

 another would cause a proportionate increase of colour to adhere, and consequently pro- 

 duce a variation of tint. This being done, the colour, which is in a state of fine powder, 

 is dusted on the oiled surface with cotton-wool ; a sufficient quantity readily attaches 

 itself, and the superfluity is cleared off by the same medium. If it be requisite to 

 preserve a panel ornament or any object white upon the ground, an additional pro- 

 cess is necessary, called ' stencilling.' The stencil (generally a mixture of rose-pink, 

 sugar, and water) is laid on in the form desired with a pencil, so as entirely to protect 

 the surface of the ware from the oil, and the process of ' grounding,' as previously 

 described, ensues. It is then dried in an oven to harden the oil and colour, and 

 immersed in water, which penetrates to the stencil, and, softening the sugar, is then 

 easily washed off, carrying with it any portion of colour or oil that may be upon 

 it, and leaving the ware perfectly clean. It is sometimes necessary, where great 

 depth of colour is required, to repeat these colours several times. The ' ground- 

 layers ' do generally, and should always, work with a bandage over the mouth to 

 avoid inhaling the colour-dust, much of which is highly deleterious. ' Bossing ' is 

 the term given to the process by which the level surfaces of various colours so 

 extensively introduced upon decorated porcelain are effected. The ' boss ' is made 

 of soft leather. 



The process of gilding is as follows : The gold (which is prepared with quick- 

 silver and flux) when ready for use appears a black dust; it is used with tur- 

 pentine and oils similar to the enamel-colours, and like them worked with the ordinary 

 camels'-hair pencil. It flows very freely, and is equally adapted for producing broad 

 massive bands and grounds, or the finest details of the most elaborate design. 



To obviate the difficulty and expense of drawing the pattern on every piece of a 

 service, when it is at all intricate, a ' pounce ' is used, and the outline dusted through 

 with charcoal, a method which also secures uniformity of size and shape. Women 

 are precluded from working at this branch of the business, though from its simplicity 

 and lightness it would appear so well adapted for them. Firing restores the gold to 

 its proper tint, which first assumes the character of ' dead gold : ' its after brilliancy 

 being the result of another process, termed ' burnishing." 



Glazing. A good enamel is an essential element of fine pottery and porcelain ; it 

 should experience the same dilatation and contraction by heat and cold as the biscuit 

 which it covers. The English enamels contain nothing prejudicial to health, as many 

 of the foreign glazes do ; no more lead being added to the former than is absolutely 

 necessary to convert the siliceous and aluminous matters with which it is mixed into a 

 perfectly neutral glass. 



Three kinds of glazes are used in Staffordshire : one for the common pipe-clay or 

 cream-coloured ware ; another for the finer pipe-clay ware to receive impressions, 

 called printing body ; a third for the ware which is to be ornamented by painting with 

 the pencil. 



The glaze of the first or common ware is composed of 53 parts of white lead, 16 of 

 Cornish stone, 36 of ground flints, and 4 of flint-glass ; or of 40 of white lead, 36 of 

 Cornish stone, 12 of flints, and 4 of flint- or crystal-glass. These compositions are not 

 fritted ; but are employed after being simply triturated with water into a thin paste. 



The following is the composition of a glaze intended to cover all kinds of figxires 

 printed in metallic colours : 26 parts of white felspar are fritted with 6 parts of soda, 

 2 of nitre, and 1 of borax; to 20 pounds of this frit, 26 parts of felspar, 20 of white 

 lead, 6 of ground flints, 4 of chalk, 1 of oxide of tin, and a small quantity of oxide of 

 cobalt, to take off the brown cast, and give a iaint azure tint, are added. 



The following recipe may also be used : Frit together 20 parts of flint-glass, 6 of 

 flints, 2 of nitre, and 1 of borax ; add to 12 parts of that frit, 40 parts of white lead, 

 36 of felspar, 8 of flints, and 6 of flint-glass ; then grind the whole together into an 

 uniform cream-consisteuced paste. 



As to the ware which is to be painted, it is covered with a glaze composed of 13 

 parts of the printing-colour frit, to which are added 50 parts of red lead, 40 of 

 white load, and 12 of flint ; the whole having been ground together. 



The above compositions produce a very hard glaze, which cannot be scratched by 

 the knife, is not acted upon by vegetable acids, and does no injury to potable or 

 edible articles kept in the vessels covered with it. It preserves for an indefinite time 

 the glassy lustre, and is not subject to crack and exfoliate, like most of the Conti- 

 nental stoneware made from common pipe-clay. 



In order that the saggers in which the articles are baked, after receiving the glaze, 

 may not absorb some of the vitrifying matter, they are themselves coated, as above 

 mentioned, with a glaze composed of 13 parts of common salt and 30 parts of potash, 

 simply dissolved in water, and brushed over them. 



YOI. in. s s 



