Fig. 9. Copper Pickle Pan.
Any picture desired may now be painted on the enamel surface, either with ordinary china paints or finely ground enamel “slimes” mixed with oil of cloves or oil of lavender. This painting may be done with a small camel’s-hair brush and when finished should be fired until the enamel fuses. The piece should be allowed to cool slowly and when cool should be charged with a coat or two of clear fondant which, after being fired, may or may not be stoned and polished, as the artist sees fit. If the painting requires it, it may be touched up and fired several times before being charged with the fondant, but the fewer times a piece is fired the less chance there is for accidents which may prove fatal to the work of art.
If the metal used is very thin, it will be necessary to enamel it on the back as well as on the front, for a thin piece of metal which is enameled on one side only will warp out of shape, but if enameled on both sides will keep its shape perfectly. Of course the enamel on the back may be of any color and need not be finished carefully, as it is there for use not ornament.
An enamel painting must be fired with great care. First it must be warmed by degrees before put into the muffle, so that the oil may have a chance to evaporate. It should then be placed partly in the muffle and not put way in and should not be heated to a red heat until the residues of the oils shall have burnt away. If too hot a muffle is used, or if the piece is fired too long, the painting will appear blurred and faint. If the painting appears blistered after firing, it is due to the fact that the oils used contained too much carbonaceous residue.
The fondant used on an enamel painting should be very finely ground, much more so than for ordinary work, and the first layer of fondant should not be fired to smoothness but only until it just begins to flow, as was the case with the painting itself. The last layer of fondant should of course be fired as smooth as possible.
If a large number of pieces are to be painted with the same design, there are a number of mechanical means that can be used to take the place of free-hand painting. We will outline one of these processes, which is as follows.
Etch a copper plate with the outline of the design that is to be painted on the enamel. The etching on the copper plate must be a positive, not a negative; that is, the design must appear on the plate as it is to appear on the enamel and not reversed as in ordinary etching. The design must also be exactly the same size as the one to appear on the enamel.
The lines in the etching should now be filled with finely ground enamel paints mixed with oil of cloves or some such medium. It is best to use paint of the color that is to predominate in the picture, although in some cases it will be found that black will give the best working outline.
When the lines of the etching are filled with the paint, the plate should be scraped smooth so that no paint remains on it except in the etched lines. The plate should now be pressed against a piece of thin, smooth, sheet rubber, to which the paint will stick in preference to the copper plate, thus transferring the design to the sheet of rubber, where it appears reversed.