The Scientific American 35, 22.5.1847
(Continued from No. 34.)
To Enamel Picture Glasses with Gold.
The glass must be first washed perfectly clean and dried; then moisten it by breathing on it, or wet it with the tongue, and immediately lay on a leaf of gold, and brush it down smooth. When this is dry, draw any letters or flowers on the gold with Brunswick blacking, (a solution of gum asphalum with spirits turpentine) and when dry, the superfluous gold may be brushed off with cotton, leaving the figures entire. Afterward the whole may be covered with blacking, or painted in any color, while the gold figures will appear to advantage on the opposite side of the glass.
This work may be elegantly shaded by scratching through the gold with a steel instrument, in the end of which many sharp points are formed, previous to laying on the blacking.
Oil paints of any kind may be substituted in the place of the blacking, but will not dry so quick. Silver leaf may be managed in the same manner; but if coloring is required on the silver, the coloring laquers must be spread on the parts requiring it, before the silver is applied. Splendid ornaments may be produced in this way, by first drawing the outlines as described in painting on glass: and having judiciously applied the laquers, the leaf—gold or silver—may be laid over the whole as above described. Then if any fine black lines or deep shading is required, it may be effected by scratching through the leaf with a pointed instrument, and finished by a full coat of blacking over the whole: it being understood, of course, that the ornament is to appear from the opposite side of the glass.
Bronzing on glass.
For this purpose the glass may be sized with a very thin coat of dilute copal varnish, and when the varnish is nearly dry, the bronze may be applied through stencils, as described in ornamental bronzing: but if the bronzed figures are to be colored, the outlines of the figures must be first drawn, and the several points stained with laquers, before the glass is sized for the bronze. After the bronze is applied, the figures may be painted with opaque or body paints, and a final coat laid over the whole. If any fine lines of bronze are required in the finishing, the paint may be scratched through with a point as before described, and these lines being slightly sized, the bronze may be applied to the lines without a stencil. The most beautiful figured borders may be formed by means of stencils finely cut for that purpose, the bronze' being applied through the apertures: and such border figures may be further beautified by having fine line figures drawn with a point through the bronze, prior to the final coat of black, by Which the work is finished. The practitioner will find in this branch, a field for an infinite variety of beautiful fancy work, which will afford both amusement and utility.
Transparent painting on cambric.
This art is extensively practised in painting screens and window shades. The cambric or muslin is prepared by being stretched on frames of convenient size, being secured by tacks at the edges, and sized with a mixture of fine flour paste, white glue and white bar soap, in the proportion of one pound of flour to four ounces of glue and five ounces of soap. The soap must be of the white or transparent kind, and serves to soften the other ingredients and render the cloth pliable and elastic. The flour is first made into paste, and while hot, the soap is added, with a few drops of essence of cinnamon, essence of lemon or lavender, to prevent unpleasant perfumes. The glue is to be dissolved by itself, and then the whole is mixed together, and diluted with water till it will work freely with a common paint brush, while cold. A thin sizing is spread on the work side of the cambric: and if the sizing is well proportioned and applied, it will be nearly invisible when dry. A coat of pure linseed oil, diluted with an equal quantity of spirits of turpentine, may be applied to the whole surface, or only such parts of it as are intended to receive the coloring; it must be applied quickly and uniformly, that the transparency may be equal in all parts; and if a little copal varnish be mixed with the oil it will be the better. The frame, with the cambric, must be placed between the artist and the principal light, that the lights and shades may be seen distinctly during the process of painting. The colors used in this branch, generally consist of Ivory Black, Prussian Blue, Ultramarine, Paris Green, Crystals of Verdigris, Gamboge or Turmeric, Lake, Umber, and Burnt Umber, Terra de Sienna and Burnt Terra de Sienna, and Gum-asphaltum or Brunswick Blacking. (The Turmeric is prepared by steeping it in alcohol, and straining off the liquor, which may be then mixed with oil or varnish.) These colors are ground in oil, diluted with spirits of turpentine, to which may be added a little drying japan or white vitriol, to hasten the drying of the colors. An outline of the design is drawn with a hair pencil with dilute umber or ivory black; after which the colors are applied, more or less dilute, as more or less transparency is required. In general, the brightest colors should be applied first, and afterward the darker shades or colors. The operator will find it requisite to turn the workside to the light occasionally, to see whether the opaque surface of the coloring and shading corresponds with the transparent view; for it is the peculiar property of good work of this kind, to appear equally well in a transparent or opaque view. In regulating the shades for the purpose, it is sometimes requisite to mix white lead with the colors, which increases the shade in the transparency, while it reduces it in the opaque. Stencils, in sets made to match, are used with advantage in this branch, especially in the formation of borders and scroll embellishments The colors must be applied with soft brushes, and laid smoothly; and if any part ieceives too dark a coloring, the only remedy is to scrape off the paint from such parts before it is dry. The best designs for window shades, consist of landscape views, and should be always designed to accommodate the form and position of the ground on which they are drawn. Wall regard to the rules of coloring and shading landscape views, we must refer the reader to our next number.
(To be continued.)
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