Making Bricks by Hand.
In the mechanical arrangements for making bricks two very different systems are adopted; the one handicraft, and the other by machinery. The former has always been and still is far more extensively adopted than the latter.
In the selection of materials for brick-making, a brown loamy clay, that is, clay which contains a small quantity of calcareous matter, is considered best for ordinary bricks, but the ingredients vary according to the purposes for which the brick is required; and every one must have remarked the difference in colour between the light yellow marl stocks, as they are called, employed in the facing of houses of the better kind, and the dark red brick used in Lancashire and other northern counties. The colour also varies with the proportion of ashes or sand employed in the mixture, and with the degree of heat they are subjected to in drying. The general process is, however, much the same everywhere; and we shall describe that used in England, where bricks are always burnt.
The proper kind of clay being found, the top vegetable mould is removed, and the earth dug and turned over to expose it as much as possible to atmospheric action, and for this purpose it is left for the winter. In spring, a quantity of fine ashes, varying in proportion to the clay from one-fourth to a fifth, according to the stiffness of the latter, is added by degrees, and well incorporated by digging and raking, water being poured on to render the mass soft. When the union is effected, the clay is carried in barrows to a rude mill, erected near the shed, in which the brickmaker works.
This mill consists usually of a vat, or circular vessel, fixed on a timber frame; an upright iron axle is placed in the centre of the vat, and carries some iron plates, or rakes with teeth, to stir up the soft clay when placed in the mill: this axle is turned round by a horse harnessed to a horizontal shaft which proceeds from the axle. The clay being put into the vat, the rakes or knives complete the incorporation of the ashes, and thoroughly temper the whole mass, which is gradually squeezed out through a hole in the bottom of the vat.
A better kind of mill is used in tempering the material for the better bricks; it only differs, however, in being larger. An iron harrow loaded with weights is dragged round in a circular pit lined with brick-work. The clay in this case is diluted with water sufficiently to allow of the stones sinking to the bottom; and the fluid is drawn off into pits, where it is left to settle and thicken, to the proper consistence.
The prepared clay is first separated into masses, each large enough to make a brick, by the feeder, or assistant, who sands the pieces ready for the moulder; the mould is an open rectangular box, the four sides of which are made to separate from the bottom, to allow of the brick being turned out. The bottom is now made with a lump raised on it, by which a slight depression is formed on one side of the brick, to admit a mass of the mortar being received and detained in it when the wall is built.
The moulder takes the piece of clay prepared for him, and dashing each into the mould so as to cause it to fill it, removes the superfluous quantity by means of a flat piece of wood which he draws across the open side of the mould; this strike is kept in a bowl of water to wet it, and prevent the adhesion to it of the clay. The man then lifts off the sides of the mould, and deposits the brick on a flat pallet-board, and this is removed by a boy who ranges the bricks on a lattice frame set sloping on the barrow in which they are to be taken to the field to dry; fine sand is strewed on the frame and over the bricks, to prevent their adhering together.
The bricks are taken to the field, and piled in long lines called hacks. This is a nice operation, as the soft bricks, if handled roughly, would become twisted, and rendered useless; the bottom course of bricks is raised a few inches to keep it from the wet; and the ground is prepared to receive them by being covered with dry brick-rubbish or ashes, and raked smooth. The bricks are set alternately in rows lengthwise and crosswise, with intervals between them of an inch or more, to allow a thorough circulation of air: the hack, when raised about a yard high, is covered over with straw to throw off the rain.
If the weather be favourable, ten or twelve days are enough to dry the bricks in the hacks sufficiently to prepare them for burning, but they should be thoroughly dry, or the subsequent process will fail.
Ordinary bricks for building are burnt in clamps, which are large oblong masses, built up of the unburnt bricks, laid regularly in layers, with large flues or passages at intervals, in which ashes, cinders, coal, and brush-wood are laid; layers of ashes are strewed over those of the bricks. The object is, that the fire, when the fuel is ignited, may penetrate every part of the mass, and bake every brick equally; even the ashes mixed up in the clay are intended to be partly burnt by the heat. In clamps well constructed the outside is coated with clay or plaster to keep in the heat, and when the fuel is thoroughly lighted, the external apertures should be stopped up.
The clamp when completed contains from 100,000 to 500,000 bricks. The fire will continue burning about three weeks, if the pile has been well constructed: when all smoke ceases to rise, the clamp is taken down when cold, and the bricks sorted; for, even with the utmost care, it must happen that the bricks are not all equally burnt. The best are those in the centre. The under-burnt ones are reserved to be rebuilt into a new clamp for further baking, and those which are over-done, and have run together by partial vitrification, are sold at a cheap rate for making foundations for houses, roads, &c.
The better or peculiar kinds of bricks, as well as tiles of all kinds, are burnt in kilns instead of clamps. These kilns, though of a peculiar form, according to the purpose to which they are applied, yet do not differ in principle from the lime-kiln, &c. In the kiln, the fire is not intermixed with the bricks, but is applied beneath; nor are ashes mingled with the clay of which kiln-burnt bricks are made.
As the general principles are the same in making tiles and bricks, we shall class all these coarse pottery-works together here, in an enumeration of the most important kinds used in Britain.
Place-Bricks are the worst of the clamp-burnt stocks, and are used for common walls, and the poorest kinds of work; they are soft and unequally burnt; they sell from 20s. to 30s. a thousand.
Stock-Bricks are those from the centre of the clamp, and are regularly burnt, of an equally hard texture, and even colour; they are used for good work of all kinds; the price varies from 30s. to 40s. a thousand.
Malm-Stocks are clamp bricks, but made with more care from clay to which ooze, chalk, or marl is added; and the whole carefully tempered; they are of a fine clear yellow colour, and are used for facing the walls of good houses, and for making arches over doors and windows in general, where they are to be seen. The softest kind are called cutters, from their admitting of being cut, or trimmed, with the trowel with nicety. The prices of these bricks vary greatly.
Fire-Bricks are made of a peculiar kind of clay, found in perfection at Windsor, Stourbridge, and parts of Wales, whence the varieties derive their names. They are formed from the clay without any admixture of ashes, and are always kiln-burnt. They vary in size, and are used for building furnaces, ovens, boilers, &c.
Pan-Tiles are tiles, the cross section of which may be represented thus.
They are used for roofing outhouses, stables, &c., the edges of one row overlapping those of another next it, and they are always set in mortar: the end of the tile is formed with a projecting knob or fillet, by means of which the tile is hooked on to the batten or lath. These tiles are much larger than the Plain-Tiles, which are used in roofing dwellings, &c.; they are flat, as the name indicates, and are fixed to the laths of the roof by wooden pegs, two holes being left in the tile for that purpose. Foot and ten-inch tiles are thick square tiles of those dimensions, used for paving, hearths, &c., or for coping walls. All tiles are burnt in a kiln.
Bricks made in Great Britain are charged with a duty, and as it constitutes an important item in the revenue, the manufacture is laid under strict surveillance by the Excise. The duty on tiles was repealed in the year 1833. Bricks can only be made at certain seasons, in certain quantities, and even the screen through which the ashes are sifted, to be mingled with the clay, must be made of wire of a certain mesh. Bricks made larger than the standard measure of 8½ inches long, 4 wide, and 2½ thick, pay a higher duty than the common ones; if the bricks are smaller than the proper size, the maker is fined heavily. No duty is charged upon bricks made in Ireland.
About 1500 millions of bricks, 42 millions of plain, 23 millions pan, and 6 millions of other tiles, are made annually in Britain. A good moulder can make from 5000 to 6000 bricks in a day, from five A.M. to eight P.M.
Within the present century, the annual use of bricks in Great Britain has more than doubled, owing to the increase of manufactories, and to the construction of railroads and other public works.