136 



POTTERY. 



Pottery, slant and continued agitation in this vat, the finer parts 

 -Y~ ' of the clay amalgamate completely with the water, and 

 form a fine pulp ; while the gross and strong particles, 

 from their gravity, remain at the bottom as refuse. 

 The pulp is now conveyed from this vat through a 

 series of sieves of different degrees of fineness, and 

 moved backward and forward by machinery, till the 

 grosser parts are entirely separated from those of which 

 the stoneware is to be composed. 



Flint, as already mentioned, is an indispensible in- 

 gredient in the composition of stoneware. In prepar- 

 ing it, it is first placed in a kiln and raised to a red heat, 

 when it is thrown in this state into cold water. This 

 process is to diminish its cohesiveness, that it may be 

 the more easily reduced to powder. The flint is now, 

 by a process exactly similar to that described in regard 

 to clay, reduced to a pulp, and the gross parts separated 

 from the fine, which latter is that used in the formation 

 of the ware. This pulp, as well as that of the clay, 

 must always be made into a certain consistence, with a 

 view to ascertain exactly what quantity of each is con- 

 tained in a given measure. The two pulps are now 

 mixed together in such proportions that the flint is as 

 one to five or one to six of clay ; and they are caused 

 to amalgamate by an operation similar to that employed 

 for mixing clay and water, as recently described. 



Flint and clay being thus mixed, the next step is to 

 separate the water from them, which is effected by eva- 

 poration. When the operation has been continued till 

 the substance is sufficiently dense and stiff, it is cut out 

 in cubical figure?, and subjected to a process, the ob- 

 ject of which is to render the mass of uniform consist- 

 ence, and fit for working. This result may be attained 

 either by the hand, or more easily and efficiently by a 

 machine formed for the purpose. The nature of this 

 operation is simple. A mass of the consistence is taken 

 between the two hands, and being separated is re-united 

 with great violence, but at different parts from those at 

 which it was disjoined. It is again separated and again 

 united, and, as before, the points of contact must be 

 different. This process being repeated twenty or thirty 

 times, the mass has assumed such a uniformity in its 

 different parts, that though it originally consisted of 

 two pieces, one black and the other brown, the colour 

 of both at the end of the operation will be exactly 

 and entirely the same. The masses thus mixed and 

 prepared, are allowed to remain some time ere they are 

 converted into vessels, it having been ascertained that 

 they work the more easily from continuing a while un- 

 touched while in this state. 



These substances it is now the duty of the potter to 

 form into articles of various shape. This may be ef- 

 fected in one of three ways, either by throwing, press- 

 ing, or casting. The first of these, or throwing, is 

 performed on a machine, denominated the potter's lathe, 

 of which there are two kinds, in both of which many 

 important improvements were made by Mr. Wedge- 

 wood. The ware to be made in this way are first 

 roughly formed on one of these lathes, and after this 

 operation, are allowed to dry to a certain extent; but 

 when they come to what is called the green state, or 

 to a given degree of tenacity and stiffness, they are ap- 

 plied to the other lathe, called a turning lathe. The 

 vessels are on this lathe turned to their proper shape, 

 and obtain a considerable degree of smoothness, and 

 when removed from it, are burnished with a, smooth 

 .steel surface. The same degree of dryness at which 

 the vase requires to be applied to the turning lathe, is 

 the proper state for fixing on the handles and 



3 



Various 

 ways of 

 forming 

 the ware 

 Throwin 



other appendages. These parts, previously made and Pottery, 

 reduced to a proper degree of dryness, are attached to *-Y -' 

 the vase by means of a pulpy mass of clay mixed with 

 water, termed slip. All kinds of mountings, however, 

 are formed on the wheel or lathe by applying to the 

 vessel when the wheel is turning round, a piece of 

 wood or iron of the form meant to be communicated. 

 The juncture is smoothed with a wet sponge. The 

 vessels are now removed to a stove, varying from 80 

 to 90 degrees of temperature. Articles of a superior 

 quality, when fully dried in this stove, are rubbed over 

 with a small bundle of hemp, in order to smooth them 

 thoroughly, and to remove those inequalities by which 

 the surface may be marked. 



Vessels of a circular form are the only kind made by Pressing, 

 throwing or by the lathe. Those that have flat sides, 

 or are of an oval shape, are the result of the second me- 

 thod, or of pressing, which is done with moulds. The 

 moulds, which are made of plaster, consist of two se- 

 parate halves, one half of the figure being respectively 

 on the two sides of the mould. The clay is formed 

 into two flat pieces, of the thickness of the vessels 

 meant to be made ; these pieces are now pressed se- 

 verally into the two sides of the moulds ; the halves of 

 the moulds being now brought together, the clay is 

 also united ; and after a complete juncture has been 

 effected, the mould is removed, and the vessel has at- 

 tained its proper shape and figure. The vessels are now 

 polished, are, if thought proper, adorned with handles, 

 spouts, &c. and are removed to the stove, as in the 

 former operation. 



"The only other way of producing this ware is by Casting, 

 casting, which is simple as those already described, and 

 regarded by some as producing vessels of greater ele- 

 gance. The pulp is poured into a mould of plaster til! 

 the cavity is quite full. That part of the pulp conti- 

 guous to the mould, which must be of a certain degree 

 of dryness, is absorbed, leaving the clay or sediment 

 on the surface of the mou\d of considerable consistence. 

 The liquid part of the pulp is now poured out ; that 

 which remains becomes rapidly stiffer, and in a few 

 minutes, the moulds being removed, the vessel is com- 

 pletely formed, its exterior being the exact shape of 

 the mould, and its thickness in proportion to the time 

 allowed to the operation. These vessels, after being 

 polished and receiving handles, &c. if thought necessary, 

 are transferred to the stove ; and as, in the former in- 

 stances, are, when sufficiently dried, ready for the kiln, 

 to be converted from a soft and tender state to a hard 

 substance called biscuit. 



The next step of the process, therefore, is the sur5- Kiln or 

 jecting of these vessels to heat in the kiln ; a building furnace, 

 of a cylindrical cavity, with a flattish dome, differing 

 somewhat in its external, and a little in its internal, ar- 

 rangement from the furnaces described under the arti- 

 cle PORCELAIN, but conducted so much on the same 

 general principles, that any minute description of it 

 here would be unnecessary. The vessels are here, as 

 in the porcelain manufacture, put into cases or saggars, 

 and arranged in piles, leaving suffcient interstices for 

 the flame to insinuate itself equally in all directions. 

 The fire is continued from twenty-four to about forty- 

 eight hours ; the saggars are not removed till perfectly 

 .cool ; and the ware, when brought from the kiln, is 

 termed biscuit ; a state in which it is unfit for use, 

 being so permeable as to be accessible to water and 

 other liquids. In making the commonest stoneware, 

 however, it may be remarked, that the vessels are placed 

 in the kUn, exposed to the naked fire without being 



