SODIUM CITRATE RESTRAINER.
Citric acid 720 grains Sodium bicarbonatef 884 grains Distilled water to make 21Z ounces of solution.
These solutions will keep for an indefinite period, and can be diluted by adding five parts of water. The advantage of these last three restrainers is that when a negative shows plenty of detail, but refuses to gain in density, the addition of a little of one of the dilute solutions may be made, and the plate left for hours, if necessary, till the required density is obtained, without the slightest sign of fog.
In the collodion process, the action of the developer is usually restrained by the addition of some thickening substance, such as sugar, gelatine, etc. The collodial restrainer introduced by Carey Lea has found considerable favor among photographers.§ It is prepared by first soaking an ounce of French glue in one and a half ounces of water, to which one drachm of sulphuric acid has been added. When it has swollen up thoroughly, the water is boiled until the glue is dissolved. Another half an ounce of distilled water is then added, and the boiling continued a couple of hours. Eighty grains of granulated zinc are next added, and the boiling again con. tinned for another hour and a half. The solution is then allowed to settle, and the clear fluid decanted off. To every three ounces of a fifteen grain solution of iron used in the developer one minim of this solution is added.
RETICULATION.—An effect sometimes observable on the collodion film when dry, and much resembling the pattern of crape. It is usually due to the solvents used in the manufacture of the collodion not having been sufficiently anhydrous, or it may be due to faulty pyroxyline.
RETOUCHING.—The art of retouching does not consist as is often supposed in making bad negatives into good, but in the perfection of good negatives. Under-exposed or over-exposed negatives will never give good results, however skilful the retoucher.
In landscape photography retouching should rarely be resorted to except in bringing up flat high lights, etc. Sometimes a negative can be improved considerably by coating the back
with a matt varnish or pasting a piece of tissue paper to it and working lightly with a pencil or stump over the parts that are too transparent and by cutting out those parts that are too dense.
In portrait photography, however, retouching is almost an absolute necessity, as it is almost an impossibility to obtain truthful and satisfactory portraits by photographic means alone. We are well aware that one of the principal drawbacks in photography is its failure to represent colors in the same relative value as seen by the eye. In portrait photography, this defect is ap parent to a considerable degree. For instance, fair complexioned sitters possessed of ruddy faces, come out dark, freckles appear as prominent black spots, pimples, blotches, wrinkles and facial lines often appear so exaggerated as to be positively objectionable, and alter the appearance of the sitter to a considerable extent.
The object of retouching is, briefly, to remove these effects by the judicious use of a sharply pointed lead-pencil, without, however, destroying the likeness to the sitter, which many retouchers are apt to do.
For this purpose a retouching desk or easel is required, upon which the negative can rest firmly, and is lighted up with a reflector placed behind, so that the image can be properly seen by the worker.
The negative to be retouched is first varnished, and, when dry, the parts to be treated are dusted over with a little finely-powdered cuttle-fish. This is gently rubbed with the finger until the film has a rough appearance when viewed under a magnifying glass. Instead of this a retouching medium or matt varnish can be used.
The pencils used are usually very hard, Hardtmuth's or Faber's ;* HHH to HHHHHH are most suitable. The pencil should be sharpened in to a long fine paint, and then kept in order by oc casionally rubbing on a piece of fine emery paper.