MOULD, or Mold, in the mechanical arts, is a cavity artificially cut, with a design to give its form or impression to some softer matter applied therein. Moulds are implements of great use in sculpture, foundery, and other arts. The workmen employed in melting the mineral or metallic ore dug out of mines have their several moulds to receive the melted metal as it comes out of the furnace; but these are different according to the diversity of metals and works. In gold mines they have moulds for ingots, in silver mines for bars, in copper and lead mines for pigs or salmons, in tin mines for pigs and ingots, and in iron mines for sows, chimney backs, anvils, caldrons, pots, and other large utensils and merchandises of iron, which are here cast, as it were, at first hand.

Moulds of founders of large works, as statues, bells, guns, and other brazen works, are of wax, supported within-side by what we call a core, and covered without-side with a cape or case. It is in the space occupied by the wax, which is afterwards melted away to leave it free, that the liquid metal runs, and the work is formed, being carried thither through a great number of little canals, which cover the whole mould.

Moulds of moneyers are frames full of sand, in which the plates of metal are cast which are intended to serve for striking species of gold and silver.

A sort of concave moulds made of clay, having within them the figures and inscriptions of ancient Roman coins, are found in many parts of England, and supposed to have been used for casting money. Mr Baker having been favoured with a sight of some of these moulds discovered in Shropshire, bearing the same types and inscriptions with some of the Roman coins, gave an account of them to the Royal Society. They were found in digging for sand, at a place called Ëyton in Shropshire, about a mile from the great Watling-street Road. They are all of the size of the Roman denarius, and of little more than the thickness of our halfpenny. They are made of a smooth pot or brick clay, which seems to have been first well cleansed from dirt and sand, and well beaten or kneaded, to render it fit for taking a fair impression. There were a great many of them found together, and some have not unfrequently been found in Yorkshire; but they do not seem to have been met with in any other place, except at Lyons, where several are said to have been discovered. They have been sometimes found in great numbers joined together side by side, on one flat piece of clay, as if intended for the casting of a great number of coins at once; and both these, and all the others that have been found, seem to have been of the Emperor Severus. They are sometimes found impressed on both sides, and several have the head of Severus on one side and a well-known reverse of his on the other. They seem plainly to have been intended for the coinage of money, though it is not easy to say in what manner they can have been employed for that purpose, especially those which have impressions on both sides, unless it may be supposed that they coined two pieces at the same time by [7:15:582]the help of three moulds, of which this was to be the middle one. If, by disposing these into some sort of iron frame or case, as our letter-founders do the brass moulds for casting their types, the melted metal could be easily poured into them, it would certainly be a very easy method of coining, as such moulds require little time or expense to make them, and therefore new ones might be supplied as often as the old ones happened to break.

These moulds seem to have been burned or baked sufficiently to make them hard; but not so as to render them porous like our bricks, whereby they would have lost their smooth and even surface, which in these is plainly so close, that whatever metal should be formed in them would have no appearance like the sandholes by which counterfeit coins and metals are usually detected.

Moulds of founders of small works are like the frames of coiners. It is in these frames, which are likewise filled with sand, that their several works are fashioned; and when the two frames of which the mould is composed are rejoined, the melted brass is run.

Moulds of letter-founders are partly of steel and partly of wood. The wood, properly speaking, serves only to cover the real mould which is within, and to prevent the workman, who holds it in his hand, from being incommoded by the heat of the melted metal. Only one letter or type can be formed at once in each mould.

Moulds, in the manufacture of paper, are little frames composed of several brass or iron wires, fastened together by another wire still finer. Each mould is of the dimensions of the sheet of paper to be made, and has a rim or ledge of wood to which the wires are fastened. These moulds are more usually called frames or forms.

Moulds, with furnace and crucible makers, are made of wood, of the same form with the crucibles, that is, in the form of a truncated cone; they have handles of wood to hold and turn them with, when, being covered with the earth, the workman has a mind to round or flatten his vessel.

Moulds for leaden bullets are little iron pincers, each branch of which terminates in a hemispherical concave, and these when shut form an entire sphere. In the lips or sides where the branches meet is a little jet or hole, through which the melted lead is conveyed.

Laboratory Moulds are made of wood, for filling and driving all sorts of rockets, cartridges, and fuses.

Glaziers ’ Moulds. The glaziers have two kinds of moulds for casting their lead in. In the one, they cast the lead into long rods or canes fit to be drawn through the vice, and the grooves formed therein; and this they sometimes call ingot-mould. In the other, they mould those little pieces of lead a line thick and two lines broad, fastened to the iron bars. These may also be cast in the vice.

Goldsmiths’ Moulds. The goldsmiths use the bones of the cuttle fish to make moulds for their small works, which they do by pressing the pattern between two bones, and leaving a jet or hole to convey the metal through, after the pattern has been taken out.

Moulds, amongst masons, are pieces of hard wood or iron hollowed within-side, corresponding to the contours of the mouldings or cornices to be formed.

Moulds, amongst plumbers, are the tables upon which they cast sheets of lead, and which they sometimes call simply tables. Besides these, they have other real moulds, with which they cast pipes without soldering.

Moulds, amongst the glass-grinders, are wooden frames, on which they make the tubes wherewith they fit their perspectives, telescopes, and other optic machines. These moulds are cylinders, of a length and diameter according to the use they are to be applied to, but always thicker at one end than the other, to facilitate the sliding. The tubes made on these moulds are of two kinds; the one simply of pasteboard and paper, and the other of thin leaves of wood joined to the pasteboard. To make these tubes to draw out, the last or innermost only is formed on the mould; each tube made afterwards serving as a mould to that which is to, go over it, but without taking out the mould from the first.

Moulds used in basket-making are very simple, consisting ordinarily of a willow or osier turned or bent into an oval, circle, square, or other figure, according to the baskets, panniers, hampers, and other utensils intended. On these moulds they make, or more properly measure, all their work; and accordingly they have them of all sizes and shapes.

Mould, in ship-building, a thin, flexible piece of timber, used by shipwrights as a pattern whereby to form the different curves of the timbers, and other compassing pieces in a ship’s frame. There are two sorts of these, viz. the bend mould and hollow mould. The former of these determines the convexity of the timbers, and the latter their concavity on the outside, where they approach the heel, particularly towards the extremities of the vessel. The figure given to the timbers by this pattern is called their bevelling. Moulds, amongst tallow-chandlers, are of two kinds. The one for the common dipped candles, being the vessel in which the melted tallow is disposed, and the wick dipped, is of wood, of a triangular form, and supported on one of its angles, so that it has an opening of near a foot a-top. The other, used in the fabric of mould candles, is of brass, pewter, or tin. 1 Mould, amongst gold-beaters, a certain number of leaves of vellum or pieces of gut, cut square of a certain size, and laid over one another, between which they put the leaves of gold and silver which they beat on the marble with the hammer.