To make the actual reducer, 15 parts of each solution are mixed together and diluted with 120 parts of water. This mixture is first thick and green, but gradually becomes clear yellow, in which condition it should be flooded over the print, previously moistened with water. The action of the reducer is to convert the image, or part of it, into chloride of silver, which must of necessity be dissolved by ordinary hypo. Care must be exercised that reduction is not carried too far.
Be/itzski's Reducer. This is the method which in our hands has given the best results, and from the improved formula lately recommended by Herr Belitzski it is still more useful, as it may be kept in the form of a stock solution. The formula is as follows: -
Water ... ... ... ... ... 300 parts.
Potassium ferric-oxalate ...... ... 15 ,,
Sodium sulphite ... ......... 15 ,,
Dissolve, and add to the blood-red solution
Oxalic acid ... ... ... ... ... 5 parts,
and shake till the solution turns green ; pour off from any un-dissolved oxalic acid, and add
Hyposulphite of soda ... ... ... 75 parts.
When dissolved it is ready for .use. To reduce the print, as soon as removed from the fixing bath, rinse with water, flood with the above solution, and remove as soon as reduced sufficiently. The intensification of bromide prints is by no means a satisfactory process; it can rarely be effected without altering the colour of the deposit. There are one or two methods applicable.
Persulphate of Ammonium Reducer. This has the useful property of lowering the tones of the dense blacks in due ratio. In other words, it reduces the print as a whole, instead of chiefly reducing the lighter tones. In other ", words, ,the persulphate reducer does not brighten the print like other reducers. A solution of ammonium persulphate, 8 grains to the ounce of water (160 grains to a pint) is convenient, but rather a large volume should be used, and the print or prints should be kept in constant motion. All traces of "hypo" should be washed out before the persulphate reducer is employed.
Intensifying or toiling with Mercury and Re-dcvelopment.