THE BRASSFOUNDER.

Casting.

Next to iron, perhaps brass is the metal chiefly employed in the manufacture of articles of daily use, and the trade of the Brassfounder is therefore of very great importance, especially in connexion with the small metal fittings, such as catches, locks, bolts, hooks, screws, and other objects used in completing and furnishing the house.

Brass is not a pure metal, but is what is called an alloy, that is, a mixture of various metals. It is composed of copper and zinc in such proportions as may be necessary toobtain various degrees of hardness and colour, according to the use for which the compound is to be employed. The best proportions for common brass are about two parts of copper to one part of zinc. Formerly brass was made by heating copper withcalamine(which is the ore of zinc) and charcoal, but it is now formed from melting the two metals together. It is then cast into plates, which are either broken up for recasting into any required form, or rolled into sheets. Common brass is very malleable, is more easily melted than copper, and may be cast into any form. It will take a very high polish, does not rust or tarnish by exposure to the air, and, although it is durable in wear, is sufficiently soft to yield readily to the file and other tools used by the workmen. These properties make it useful for a great variety of purposes where steel or iron could not be so well employed.

Crucible. Magnet.

The smelting or mixing houses where the brass is made are fitted with air furnaces, and in some of the best workshops thecruciblesor melting pots are made ofplumbagoor pure blacklead, which, although it is more expensive, is much more durable than the Stourbridge clay, of which the commoner crucibles are formed.

A very fine quality of brass for best castings consists ofthree parts of best selected copper, and two of spelter, with some best scrap brass and a little tin; while a second quality is formed of two parts of ordinary copper and one part of spelter, melted into ingots with a proportion of scrap brass and brass filings. Before the latter are used the iron filings are separated from them by amagnet, or by a series of magnets fastened to a revolving chain frame.

The sheet brass is procured from the mills where it is rolled, and the brass wire is also supplied from the special manufactories where it is drawn ready for use.

Making Moulds.

The method ofmaking mouldsfor casting iron has already been mentioned, and those employed by the Brassfounder are quite similar, the tools used by the mould maker being thetrowel,mallet,rule, andsand hook, theshovelfor removing the sand, thebrushfor sweeping the surface, thebellowsfor blowing off the dust, and thecompassesfor measuring accurately.

Brush. Sand Hook. Compasses. Bellows. Shovel. Rule. Trowel. Mallet.

The principal materials for making foundry moulds for brass castings are fine sand and loam mixed in various proportions, according to the nature of the work. New sand is used for fine castings, old sand for ordinary work. The requisite external support is given by a couple of shallow rectangular iron frames without tops or bottoms, calledflasksorcasting boxes.

The two halves constituting a casting box carry ears corresponding exactly with one another, one set pierced with holes, the other furnished with points entering truly into these holes, and which may be made fast in them by cross-pins or wedges. One of the flasks is laid face downward on a board longer and wider than it, and is then rammed full of moulding sand; the surface is struck off levelwith a straight metal bar or scraper, a little loose sand is sprinkled upon it, and another board of proper size placed over it and rubbed down close. The two boards and the flask contained between them are turned over and the top board is taken off; the clean surface of moist sand now exposed is dusted over with perfectly dry fine parting sand, or very fine red brickdust. The patterns or models are now properly arranged on the surface of the same, the cylindrical or thick parts being partly sunk in the latter, and care being also taken to leave sufficient space between the several patterns to prevent one part breaking into the other, and also passages oringates, by which to pour in the metal and allow the air to escape. The patterns are arranged on both sides a central passage or runner, technically called aridge, from which again small lateral passages are made, leading into every section of the mould. The general surface is then properly arranged with the aid of smalltrowels, and a little fine parting sand or brickdust is shaken over it. When this has been accomplished, the upper part of the flask is fitted to the lower by the pins, and then also rammed full of mould sand. The fine dry parting sand or brickdust serves to prevent the two halves from sticking together. A board is now placed on the top of the upper half, and struck smartly in different places with a mallet, after which the upper half and its board are lifted up very gently and quite level, and then turned over, so that the upper half rests inverted on its board. The models are next removed, and channels scooped out from the cavities left by them to the hollows or pouring holes (ingates) at the end of the flask. Solidcoresof sand or metal are adjusted in the proper places when the article is required to be cast hollow (brass cocks, for instance), and also ironrails intended to have brass heads cast on them, or such other articles of iron as are required to be solidly united with the brass. The faces of both halves are now finally dusted with waste flour or meal dust; the two halves are then replaced upon each other, and the box is fixed together by screw clamps. The moulds forfine castings(articles with ornamental surfaces, as screens, sconces, bell-levers, &c.) are faced with various fine substances, such as charcoal, loamstone, rottenstone, &c. that they may retain a sharp impression; after which they are most carefully dried. For ordinary work it is generally considered better that the sand should retain a little moisture, though great care must be taken in this respect, to guard against the danger of explosion.

Braces. Set Moulds. Cores.

Themouldthen is a square frame, mostly of iron, filled with peculiar dark red sand, which is pressed into a firm mass, in which the patterns of the casting are imbedded and their perfect shape impressed. The casters work at a largetroughfilled with the sand, and the workshop, withits forge, has some resemblance to a bakehouse where black bread is being kneaded into loaves. The first mould is made for what is called the “odd side” of the pattern—that is to say (in solid castings), the lower, or inferior side—and this serves as a sort of pattern to which the moulder refers in fine castings. The pattern being lifted off or out as soon as the sand-mould is sufficiently solid, the whole surface, in which the chasing of the pattern is clearly defined, is dusted with bean-floor or pounded “pot” first, and afterwards with loam, sand, charcoal, or coal-dust. This has the effect of making a smooth surface, and effectually filling the interstices in the sand, so as to prevent any raggedness in the casting. Each mould, or rather the two sides of the mould, are then placed near the surface and slightly baked, a channel having been made in the edge of each for conducting the melted metal to the pattern. The two sides are then placed together and held firmly by their pins and sockets, and the mould is ready for the casting. The “pots,” or crucibles of greyish clay, which turn red by the action of the fire, are in the furnaces like so many tall flower-pots. The dirty yellowish brass ingots, made on the premises at a large mixing furnace, having been first placed across the tops of the pots, that they may expand before being melted, are about twenty minutes afterwards reduced to a molten mass, above which hovers a light sea-green flame mingled with streaks of brilliant colour, like the water from a dyehouse; meanwhile the moulds have been placed in a slanting position, with the opening in the side upwards, against a bank of sand or brickwork, and everything is prepared for pouring. A man, who should be strong in the wrist, stands on thefurnace, which has the openings at the top, like a French cooking-stove, and takingoff the brick covers from the square aperture, whence rushes out a tongue of green flame, lifts out thepotwith a pair oftongs, and after the dross is removed by theskimmerorgrunter, hands it to the pourer, who fills each mould in succession. The fumes which rise from the midst of the coloured fire are peculiar and penetrating, and the zinc eliminated from the molten brass falls in a metallic snowstorm, its flaky particles adhering to everything with which they come in contact, while the resistance of the sand to the metal causes a series of reports like muffled pistol-shots.

Large Tongs. Small Tongs. Pot Holes. Skimmer. Grunter.

The brass cocks and plugs used in gas-fittings are all cast in one central stem, like cherries on a stick, their hollowforms being secured by means ofcoresmade of hardened sand placed in the shape impressed in the mould. These are broken off the central stem with a pair ofpincersimmediately after casting.

The ornamental “vases” and larger ornaments which form the body of ordinary gas chandeliers and lamps are formed out of thin metal by a process called “stamping out,” the plates of metal being placed on a hollow die, upon which a heavy hammer, or rather weight, is brought down, being released from a latch and worked by the foot. The depth of the casting would make so heavy a blow necessary that there would be danger of splitting the metal, an accident which is prevented by the introduction of a leaden shape and a layer of clay, which is decreased after each blow of the hammer until the proper depth is gradually secured without injury.

The process called “reversing” is an operation which secures a hollow casting, the inner or hollow side being called the “reverse.” For this purpose a mould is made from one in wax, and the impression in the mould hardened, so that another model can be taken from it. This enables the moulder to secure a core which fits the impression in the mould, as one cup would stand inside another; and between the mould containing the sunk pattern and that with the projecting core there are placed strips of black clay, to secure sufficient thickness of metal, by not allowing the hollow to be too accurately filled. The pattern when cast is “laid out” on a hollow hemisphere of iron filled with pitch, and the irregularities of the casting removed by hand tools,files,rasps, andknives. In the case of figures, such as cupids, &c. forming ornaments for candelabra, the various limbs have often to be modelled in separate “cores,”which are afterwards baked hard, and put together like a puzzle-map, imbedded in the sand of the mould previous to casting. This requires great skill to effect successfully, and an experienced “reverser” is a man of mark in the factory.

Fork. Vent Wire. Sleeking Tool. Rasp. File. Vice. Pincers. Hammer. Double-headed Knife. Saw. Drawing Knife. Knife.

The completed castings are now removed to the chasing-room, where we may watch the gradual process of beautifying to which they are subjected, and the sharpening of the ornamental details by means oftoolandgraver, in a similarway to the first rough “laying-out,” which removes the irregularities of the pattern. The arms and branches which form a part of the gas chandelier work, as well as many of the scroll-work ornaments, are cast in halves, which are taken to the soldering-room, where a workman, seated at a forge-like furnace, heats them in the burning embers, and applies to the edges the solder, with which is mingled a flux of borax and water to secure its melting. The heat is increased by a blowpipe, which is in reality a double or jacketed tube, the inner one supplying gas, and the outer being connected with a large pair of bellows, and mixing atmospheric air with the lighted gas at the point of combustion.

The pickling room is a large shed-like place filled with tubs, troughs, and earthen pans. Into one of these, containing diluted aqua-fortis, the metal is plunged for the purpose of removing the scale produced on the surface by the action of the fire; from this it is dipped in a stronger solution, to undergo the process called “fizzing,” and its final baptism in pure acid restores the beautiful primrose colour which properly belongs to it. It is still dull, however, and goes to be “scratched,” an operation effected by means of a revolving wire-brush, turned by a wheel and treadle, and kept continually wet with water.

The ornamental processes have next to be considered, and these are many. Previous to burnishing, the work is dipped in argot or tartar (the lees of wine-casks steeped in water), so that it may be subject to a strong antioxyde. The burnishing itself produces those bright veins and ornamental surfaces so often seen in brass work, and is effected by fixing the work in a vice, and rubbing the parts of the pattern which are to be brightened with a steel toolhaving a smooth bevel edge. After being treated with ox-gall, bean flour, and acid, to remove any still adhering grease, the work is dried, by being first dipped in hot water and afterwards buried in a pan of warm sawdust. Then there is lacquering, both black and white, a simple process enough, since the lacquer is laid on with a brush, and the work dried on a warm plate. Much of the work of the Brassfounder, as far as regards these latter operations, is of course effected by machinery, but the casting itself is entirely completed by the skill of the workmen.

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