A stoneware manufactory should be placed by the side of a canal or
navigable river, because the articles manufactured do not well bear land
carriage.
A Staffordshire pottery is usually built as a quadrangle, each side
being about 100 feet long, the walls 10 feet high, and the ridge of the
roof 5 feet more. The base of the edifice consists of a bed of bricks,
18 inches high, and 16 inches thick; upon which a mud wall in a wooden
frame, called _pisé_, is raised. Cellars are formed in front of the
buildings, as depôts for the pastes prepared in the establishment. The
wall of the yard or court is 9 feet high, and 18 inches thick.
[Illustration: 899]
_Fig._ 899. A, is the entrance door; B, the porter’s lodge; C, a
particular warehouse; D, workshop of the plaster-moulder; E, the clay
depôt; F, F, large gates, 6 feet 8 inches high; G, the winter
evaporation stove; H, the shop for sifting the paste liquors; I, sheds
for the paste liquor tubs; J, paste liquor pits; K, workshop for the
moulder of hollow ware; L, ditto of the dish or plate moulder; M, the
plate drying-stove; N, workshop of the biscuit-printers; O, ditto of the
biscuit, with _o´_, a long window; P, passage leading to the paste
liquor pits; Q, biscuit warehouse; R, place where the biscuit is cleaned
as it comes out of the biscuit kilns, S S; T, T, enamel or glaze kilns;
U, long passage; V, space left for supplementary workshops; X, space
appointed as a depôt for the sagger fire-clay, as also for making the
saggers; Z, the workshop for applying the glaze liquor to the biscuits;
_a_, apartment for cleaning the glazed ware; _b_, _b_, pumps; _c_,
basin; _d_, muffles; _e_, warehouse for the finished stoneware; _f_,
that of the glazed goods; _g_, _g_, another warehouse; _h_, a large
space for the smith’s forge, carpenter’s shop, packing room, depôt of
clays, saggers, &c. The packing and loading of the goods are performed
in front of the warehouse, which has two outlets, in order to
facilitate the work; _i_, a passage to the court or yard; _l_, a space
for the wooden sheds for keeping hay, clay, and other miscellaneous
articles, _m_, room for putting the biscuit into the saggers; _m´_, a
long window; _n_, workshop with lathes and fly-wheels; _o_, drying-room;
_p_, room for mounting or furnishing the pieces; _q_, repairing room;
_r_, drying room of the goods roughly turned; _s_, rough turning or
blocking-out room; _t_, room for beating the paste or dough; _u_,
counting-house.
The declared value of the earthenware exported in 1836, was 837,774_l._;
in 1837, 558,682_l._
There are from 33,000 to 35,000 tons of clay exported annually from
Poole, in Dorsetshire, to the English and Scotch potteries. A good deal
of clay is also sent from Devonshire and Cornwall.
The Spanish _alcarazzas_, or cooling vessels, are made porous, to favour
the exudation of water through them, and maintain a constantly moist
evaporating surface. Lasteyrie says, that granular sea salt is an
ingredient of the paste of the Spanish alcarazzas; which being expelled
partly by the heat of the baking, and partly by the subsequent watery
percolation, leaves the body very open. The biscuit should be charged
with a considerable proportion of sand, and very moderately fired.