CHROMO MAKING.
The production of chromo pictures requires a little skill. Practice is necessary. The glass plate to be used should be washed off with warm water, and then laid in a 10 per cent solution of nitric acid. After one hour, wash with clean, cold water, dry with a towel, and polish the plate with good alcohol on the inside—hollow side—until no finger marks or streaks are visible. This is best ascertained by breathing on the glass; the breath should show an even blue surface on the glass.
Coat the unmounted photograph to be colored with benzine by means of wadding, but without pressure, so that the retouching of the picture is not disturbed. Place 2 tablets of ordinary kitchen gelatin in 8 3/4 ounces of distilled or pure rain water, soak for an hour, and then heat until the gelatin has completely dissolved. Pour this warm solution over the polished side of the glass, so that the liquid is evenly distributed. The best way is to pour the solution on the upper right-hand corner, allowing it to flow into the left-hand corner, from there to the left below and right below, finally letting the superfluous liquid run off. Take the photograph, which has been previously slightly moistened on the back, lay it with the picture side on the gelatin-covered plate, centering it nicely, and squeeze out the excess gelatin solution gently, preferably by means of a rubber squeegee. Care must be taken, however, not to displace the picture in this manipulation, as it is easily spoiled.
The solution must never be allowed to boil, since this would render the gelatin brittle and would result in the picture, after having been finished, cracking off from the glass in a short time. When the picture has been attached to the glass plate without blisters (which is best observed from the back), the edge of the glass is cleansed of gelatin, preferably by means of a small sponge and lukewarm water, and the plate is allowed to dry over night.
When the picture and the gelatin are perfectly dry, coat the back of the picture a few times with castor oil until it is perfectly transparent; carefully remove the oil without rubbing, and proceed with the painting, which is best accomplished with good, not over-thick oil colors. The coloring must be observed from the glass side, and for this reason the small details, such as eyes, lips, beard, and hair, should first be sketched in. When the first coat is dry the dress and the flesh tints are painted. The whole surface may be painted over, and it is not necessary to paint shadows, as these are already present in the picture, and consequently show the color through in varying strength.
When the coloring has dried, a second glass plate should be laid on for protection, pasting the two edges together with narrow strips of linen.