The rods supporting the twisted wicks, as they come from the twisting and cutting machine, are transferred to a frame capable of being raised and lowered at will. This commonly takes the form of a beam, but a better arrangement is seen in Fig. The frame, made of iron, and capable of revolving, is so suspended that a perfectly horizontal position is always maintained, even under undue pressure at either end; in this way are secured a uniform length of candle and a plumpness at the top, which is difficult of attainment, even by skilful workmen, by the ordinary beam. Under the frame are placed troughs containing melted tallow, into which the suspended wicks are repeatedly dipped. After each dipping, the adherent fat is allowed to cool sufficiently to retain a new coating on fresh immersion. The process is renewed until the candles have grown to the proper thickness; they are then left to cool and harden. Tallow dip candles are still largely manufactured, and are much employed in mines and small factories, and by domestic servants, as well as in cottages. They are also very suitable for artisans working in draughty places, as the wicks being large are not easily extinguished. They have been largely replaced for domestic use by the small moulded "cottage composites" made from distilled fatty acids, with a self-consuming wick. There is also a dip candle made from the same material, and in the same sizes as the old tallow dip, called the "snuffless dip," which, as a candle for carrying about, is superior to the paraffin candle. It is rather more expensive than the commoner paraffin, but, by the introduction of a core of softer material, the cost may be reduced. The first operation in the manufacture of these is to wind a continuous length of plaited and prepared wick around a frame of narrow, but stout, iron hoop, bent into the shape of an oblong rectangle. All the frames are of one length, but the widths vary to suit the length of the candle required. To the upper side of this frame is temporarily attached a lath or broach corresponding in length with the frame. The dipping is done at first three or four times, and when the wicks have acquired sufficient rigidity, a knife is passed along the lower side of the frame, cutting the wicks at the lower end. The iron frame is removed, and the coated wicks are left suspended on the broach. The broaches are about 3 ft. in length, and carry 40 candles each. The candles during the process of dipping are kept apart from each other by the width of the broach; and the ends of the four broaches are caught up, and kept separate, by holes made to fit them loosely in the blocks, which serve as handles wherewith to carry them, and which, in the operation of dipping, are laid on the supporting brackets of the dipping machine. Thus 160 candles are dipped at once, making 20 lb. of 8's, 16 lb. of 12's, and soon. The dipping is continued at intervals till the required weight is attained, and which is shown at once by the perfect balance. The material in the dipping trough is, by constant additions of warmer material, kept near the point of congealation. The plant required is inexpensive, consisting mainly of frames, some of them revolving on pivots, to carry the broaches with their candles while cooling, a wheel for winding wicks on frames, and a few melting tubs.
Pouring is used only with candles made of beeswax, which cannot be moulded, for the candles refuse to leave the moulds, or crack while doing so. The wicks are placed upon a horizontal hoop, and the operator, holding this with one hand, pours the previously melted wax over the wicks with the other. After three or four revolutions, that hoop is laid aside, and another is substituted. At a certain period the candles are reversed, as there is a natural tendency to thicken at the lower extremity. They are then rolled on a marble slab, under a weighted board, and are trimmed to the required length with a knife and gauge. A well-made wax candle should show rings like a tree, where the different layers have been superposed.
By far the greater number of candles now manufactured are moulded, by which they acquire a much more finished appearance. The most simple form of moulding machine is that known as the "hand-frame," which is in use among small manufacturers, and for particular kinds of candles, bought by those who, for reasons best known to themselves, prefer "hand-made" articles. The hand-frame contains from three to thirty-six mould-pipes (each making one candle), held together by woodwork, and opening into a trough at the top, their points being downwards. The wicks are cut to the proper length, and provided with a loop at one end, which is caught by a long crotchet-hook, and thus one wick is drawn into each pipe, where it is secured by a peg at the tip, and a cross-wire at the "butt" end of the candle. The frames are then heated to a temperature about 10° F. (5½° C.) short of the solidifying-point of the candle-material, which is then poured into them in the case of fatty acids, as cold as possible, provided that there are no lumps of solid fat in the material. The trough is filled full, to allow for the contraction of the candle when cold, and the superfluous material is eventually removed with a straight-edged trowel. The hand-made candle is readily distinguished by the little groove which the wire wick-holder makes in its base.
Arrangement of Plant
The arrangement of the candle factory is of j great importance. The boiling-up department must be well ventilated, so that the steam rising, from the vats does not pervade the rest of the building, and after condensing on the roofs, drop like rain on the goods. For economy of working, it should be as central as possible in relation to the moulding room. The vats should be set at such a height that the candle-material shall, by its own weight, fall or flow into the drying pans. They must be strongly built of wood, and hooped, and each heated by a perforated copper coil inside, around, and near its bottom. On the side of each vat, near the bottom, there should be a large brass cock for running off the wax, and, in the bottom, there should be a hole, fitted with a movable plug, for drawing off the water, and below, a separator, to conserve any wax which may escape with the water. This separator may extend under several vats. No iron must come in contact with the wax after it has been mixed with the percentage of stearic acid which has been added in the vats. The drying pans, steam cased as they must be, for heating, may be of earthenware or enamelled iron, or, as they are in rare cases, silver-plated. If these are placed in the moulding room, so as to do away with long hand carriage by the maker, the exhaust steam from them should be led away to a steam trap. The difficulty of connecting the drying pans to distant vats is the chemical one of getting a pipe or gutter of a metal or suitable material which shall not be affected by the fatty acid. This is sometimes overcome by keeping the stearic acid separate, and measuring it into the drying pans, but this method has disadvantages. Sometimes for common candles, American scale is wrought along with semi-refined. It must be blended in the melting-house, but the melting had better be done in the same way as recommended for scales for refining, at a point in the yard convenient to the stocks, where it can be done in an underground boiler, and blown into elevated settlers, whence it can be drawn as required. In blending paraffins of different melting points, they will be found to give a melting-point the mean of that of the ingredients, but the stearic acid mixture will lower it, whatever be its melting point.