GELATINO-CHLORIDE EMULSION PAPER.—A paper coated with a gelatino-chloride emulsion, containing a large quantity of citrate. It prints out in the same manner as with albumen paper, although much quicker. The image should be a little darker than required for the finished paper.
The prints are first washed in two or three changes of water, and are then ready for toning. Almost any toning bath can be used, the tones varying with the different formulae used, so that the operator can select any bath. The following are recommended : Keep. Nor and 2 separate. For toning take in the proportion of twenty ounces of No. to six ounces of No. 2.
After toning the prints are fixed in a solution of sodium hyposulphite, two ounces to twenty of water.
Or the following method of toning and fixing in one operation may be employed. The bath is made up of— Water 24 ounces Sodium hyposulphite 6 ounces Ammonium sulphocyanide z ounce Sodium acetate 13 ounces Alum (saturated solution) zo ounces Fill the bottle containing the solution with scraps of sensitized paper, spoilt prints, etc.,
which have not been fixed. Stand in the open air for a day, and filter. Then add— Ammonium chloride 3o grains Gold chloride 15 grains With this bath the operations of washing, toning, and fixing are reduced to one. The prints are plunged into the solution without any previous washing, and are there allowed to remain until the required tone is obtained. They are then removed and well washed.
After removing from the fixing bath the prints are well washed in several changes of water, laid in a saturated solution of alum for a few minutes. and again washed.
On removal from the final washing water the prints are squeegeed on to clean plate glass, previously rubbed with French chalk. When dry they are peeled off the glass, and will have a very high polish. For fuller description of this process see Enamelling.
If ground glass be used a matt surface is given to the prints, and they resemble an engraving.
For methods of mounting gelatino-chloride prints see Mounting.