THE BRONZING PROCESS
The implements and materials required for the bronzing process are the same as those required for gilding, with the exception of the gold leaf, the cushion knife and tips and with the addition of the BRONZE POWDERS of the necessary colors, and of COPAL VARNISH. These may be obtained from any dealer in art materials; but, of course, those of the best quality only should be used.
1.-The frame which is to be bronzed must be proceeded with in the same manner as described in the gilding process. That is to say, all imperfections must be first remedied and the frame put in perfect order.
2.-Two coats of pipe clay are then to be applied to all of the composition work, using a bristle brush for that purpose. The pipe clay is to be prepared as allready described for the gilding process.
3.-Two coats of burnish-size must next be applied all over the frame, using a bristle brush instead of a camel's hair brush on the composition parts. For the smooth parts of the frame, a camel's hair brush may be used, as a more even surface may be obtained in that way. The burnish-size should be applied very sparingly, so as not to clog up the ornamental parts of the frame. After having given the frame two thorough coats of the burnish-size, a third and final coat or the same size must be applied. To this final coat, before being applied, should be added a small quantity of powdered lampblack. The addition of the lamp black is not absolutely necessary, however, as the object for which it is used is simply to give a darker appearance to the final coat, which, in the crevices and hollows, when the whole work receives the varnish coat, then assumes that antique appearrance. The lamp black rather impairs the burnishing quality of the size, though not to any serious extent.
4.-After the final coat has been applied, put some or the bronze powder which is to be used into a small saucer. A very little bronze powder will go a great way. In another saucer, pour a weak solution of gelatine or of gum arabic. This must be just sufficiently strong to hold the bronze powder on the frame. The usual way of proceeding, in order to apply the bronze powder, is to dip the fingers first into the gelatine or gum arabic, and then into the bronze powder, and proceed to rub it on to the work to be bronzed. It may be applied with a bristle brush, and, where the powder is to be inserted into cracks and crevices, it must be so applied. The object of using the fingerscis, that withcthem a smoother and thinner coat can be obtained; and the smoother and thinner the coat, the better will it burnish.
5.- When the rrame has been completely covered and the coating is sufficiently dry, all the flat and smooth parts of the frame, and all those parts of the composition work also which are in relief, must be completely burnifhed. This part of the work requires a great deal of patience and time but one is fully repaid for the labor bestowed, in the brilliancy of the work when done.
6.-After the frame has been burnished sufficiently, a thin coat of copal varnish is to be given all over it. The varnish is intended to protect the bronze from tarnishing through contact with the air, as well as from any moisture which might accidentally get on the frame, and which, of course, would remove the film of bronze.