The quantity of lacker taken in the brush depends partly upon the experience of the operator; those who have had much practice are enabled to use the brush tolerably full of lacker, which under proper management flows freely over the surface; but those who have less experience, will be more likely to succeed when the brush is only moderately moistened, as any irregularities in its application are then less apparent.

Circular works are generally lackered in the lathe, and when the friction of polishing is not sufficient to give the necessary temperature, the arbors, screw chucks or other apparatus necessary for fixing the work in the lathe, are laid in order ready for use, after having been wiped clean with whitening as carefully as the work itself. The work, when sufficiently heated, is rapidly transferred to the lathe, finally wiped with a clean cloth, and lackered with a rather dry brush, which is gradually traversed along the work while the lathe is slowly turned in the direction to lay the hairs straight. The brush should be traversed twice over every part of the work to ensure its being uniformly covered with the lacker; should this not be the case, the surfaces will frequently exhibit prismatic colours when examined from different points of view.

The lackers, whether pale or coloured, are applied in the same manner to all works either plain or ornamented, but for mechanism the pale lackers are almost exclusively used, and the coloured lackers are principally applied to works of an ornamental character, with the view of giving a richer tint to the metal than it naturally possesses. \n some instances the colour is produced entirely by the lacker, as in wood, or leather, which are sometimes covered either with silver leaf or tin foil, and afterwards coated with a gold-coloured lacker. This constitutes a sort of fictitious gilding that is tolerably durable, but disappears on the application of alcohol or naphtha.

Ornamental works in brass, such as house furniture, lamp and gas fittings, whether stamped or cast, are, as mentioned on page 1041, generally brightened and coloured, by dipping and bronzing, which processes will be here briefly described.

After the works have been fitted together, they are annealed by heating them over the open fire to the red heat, and allowing the cooling to extend over one or two hours; but if the works should have been brazed, a longer time is allowed for the cooling. The heat employed in annealing removes any grease or dirt that may have accumulated during the processes of fitting; but annealing is inadmissible with works that have been soft soldered, as the heat would melt the solder, and therefore such works are annealed before they are fitted together, and are afterwards oiled in a ley of pearl ash to remove the grease. The work is next pickled in a bath of dilute aquafortis, which may be made with two or three parts of water to one of aquafortis; but the old acid that has been used for dipping, and contains a small quantity of copper in solution, is frequently preferred. The work is allowed to remain in the pickle for one or two hours according to the strength of the acid; but the metal must not be permitted to remain in the pickle for too long a time, or it will be eaten into holes. The entire surface of the work is next scoured quite bright with sand and water, applied with an ordinary scrubbing brush; the work is then washed and allowed to remain in quite clean water for a few minutes until the dipping bath is ready.

The dipping bath consists of pure nitrous acid, commonly known as dipping aquafortis, a sufficient quantity of which is poured into a glass or earthenware vessel to allow of the work being entirely covered with the acid, so far as the process is required to extend. If the work does not require to be wholly immersed, it is handled with the fingers, but if the entire surface is to be dipped, brass pliers are used, as the insertion of wood or iron instruments would deteriorate the acid.

The bath having been prepared, the work is taken out of the water and dipped into the aquafortis for an instant only; it is then quickly removed, plunged into clean water and well rinsed to remove the acid, for which purpose two or three vessels containing cold water and one hot water are arranged in order, and the work is transferred from one vessel to another as rapidly as possible, in order to prevent its being discoloured during its passage through the air. The more effectually to remove the acid, some manufacturers add argal to the hot water.

If the work should not appear sufficiently bright, it may be dipped a second time, but the work must be quickly removed from the acid, as it acts very energetically on the metal, and the dipping must not be repeated too frequently, or a bad colour will result, which can only be remedied by cleaning the surface a second time. Immediately after the rinsing, the work is plunged into dry beech or box wood saw-dust and rubbed until quite dry. The work is then burnished at the parts required to be bright, and lackered with as little delay as possible to prevent discoloration.

The green bronze colours, in imitation of the tints that occur on real bronze from long exposure to the atmosphere, are produced chemically on brass and gun-metal, by a variety of acid applications, but in all it is quite essential that the work should be first thoroughly cleaned from grease, and brightened either with the file or emery paper, in order to allow the acid to act uniformly on the surface. Works having ornamented surfaces to which the file or emery paper could not be conveniently applied, are generally boiled in a ley of pearlash, and afterwards scoured with clean sand and water.

Sometimes vinegar alone is used as the bronzing liquid, at other times dilute aquafortis, or a strong solution of sal ammoniac is used; but more frequently sal ammoniac and vinegar are employed together, in the proportions of from one to three ounces of sal ammoniac to a pint of vinegar, according to the taste of the operator, and sometimes a little common salt is added.