Very fine carbon proofs having the appearance of pictures on opal plates are made by transferring in the following manner, devised by the author:
Develop on the ground surface of a glass or porcelain plate, well waxed, to obtain a matt picture, or in the ordinary manner for "full gloss," and when the image is retouched or colored, apply a thin coating of gelatine, let dry and coat with the following opaque collodion:
| A. | Ether, conc. | 100 parts |
| Alcohol, 95 deg | 90 parts | |
| Pyroxyline | 7 parts | |
| B. | White zinc in very fine powder | 9 parts |
| Castor oil | 3 parts | |
| Alcohol | 10 parts |
Grind in a mortar, adding ultramarine blue and carmine, or a little of any suitable coloring matters, and mix to A. When the collodion is dry, which requires a few hours, strip the whole or back with strong white or colored paper before stripping. A solution of gelatine with glycerine, white zinc, etc., may be substituted for collodion when the pictures are employed as ornaments on wood, etc. Carbon prints on celluloid are now made for similar purposes.
| OPAL GELATINE SOLUTION | |
|---|---|
| Gelatine | 150 parts |
| Glycerine | 15 parts |
| Zinc, white | 40 parts |
| Water | 600 parts |
To which some coloring matters may be added according to taste. Grind the white with the glycerine and a little water, mix to the gelatine dissolved in the remainder of water, and filter through canvas. Apply the mixture moderately hot, 30 deg. C. (86 deg. Fahr.)
Transparencies.—The transparencies are printed on a special tissue sold under the name of “diapositive.” It differs from the ordinary tissue in this, that the mixture contains a greater quantity of the color matter, India ink, which is ground exceedingly fine.
The proofs for transparencies should be printed deeper than those to be seen by reflection, and developed on thin glass plates, free from any defects, and coated with either one of the following substrata:
| Soluble glass | 5 parts |
| White of eggs | 15 parts |
| Water | 20 parts |
The whole is beaten up to a thick froth and allowed to subside, when the clear liquid is decanted, filtered through flannel and the glass plates coated. The substratum should be allowed to dry for a few hours, and rinsed under the tap before use.