The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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citrate are soluble in water, and cause the milkiness which is apparent when chloride prints are placed in water. These should be got rid of before toning or else they contaminate the toning bath, and in the case of the alkaline baths, such as the acetate or borax, the prints must be free from any acid, or else the bath becomes acid, and tones but slowly or not at all. If the sulpho-cyanide bath be used, free silver salts mean the formation of silver sulphocyanide, the bath will not keep, and toning is rendered more difficult. In the case of the combined bath we have hypo; and to place a print containing acid in this means decomposition of the hypo and sulphurisation and degradation of the whites. As soon as sufficient prints are obtained, for it is not worth while toning one or two, make a solution of salt, ordinary household salt, 2 oz. to the pint of warm water. When dissolved and cool, place the prints in the solution and keep them on the move for ten- minutes, pour away the salt, and wash for ten minutes in plain water. The use of salt renders toning some-what slower, more even, and obviates any free soluble silver salt. If the prints are washed in water first, the salt being omitted, it is necessary to change the waters very quickly, or yellowed whites will be the result, from the silver combining with the paper and gelatine. It is preferable to use salt or carbonate of soda, the latter in the proportion of 1 oz. to the pint - I prefer the salt. Now with regard to the toning bath. When matt-surface papers were introduced, I started a series of experiments, using one print of matt and one of glossy paper, and tried the usual baths, acetate, borax, phosphate, carbonate, and sulpho-cyanide, and found that with all but the last there was a tendency to pinky tones ; and this was puzzling for some time, till the con-clusion was come to that it was due to the action of the gold upon very faint - too faint to be visible - impression of light upon the silver salt. This was confirmed by the curious pinkish tinge on vignettes. An instructive experiment was then made : a letter was cut out of deep ruby paper and placed in close contact with a sheet of paper, and the whole put out in the light and strips covered up every thirty seconds - the strip last covered just showed a very faint sign of light action. The print was washed and toned in strips, and in baths of different strengths, and after fixing three decided strips were visible with increasing pinkiness. This proves that the paper must be exposed as little as possible