Oil Colors.—The best mode of preparing a carbon print for the reception of oil colors consists in sizing it with isinglass. A solution of about two per cent, of isinglass in equal parts of hot water and spirits of wine, carefully applied (not too hot) to the surface of the carbon print, with a flat camel's-hair brush, yields a surface upon which oil colors work admirably.
Retouching Carbon Prints.—In the ordinary process of retouching carbon prints, to remove small imperfections, it is only necessary to use the proper color in the usual way; but if a little gelatine, with a trace of a chromic salt, be employed with the color, or if any good "Sizing Preparation" be employed as the medium, instead of water, the color will, when dry, become insoluble, like the rest of the picture. If the retouching be effected with the same materials before transferring the print, it will, when the picture is finished, be under the image, and no inequality of surface, usually apparent after touching, will be seen. This method permits the character of a print to be considerably modified, without the manipulation being obtrusively apparent in the finished picture.
PRACTICAL NOTES ON THE CARBON PROCESS.
TRANSFERRING WITHOUT A PRESS—TRANSFERRING WITHOUT GELATINE—CARBON PRINTS ON PORCELAIN GLASS—CARBON NEGATIVES.
Another and very interesting method of transferring prints has been tried practically, after an idea of Mr. Swan, by Dr. Vogel. The characteristic of this method is, that a press can be dispensed with.
