This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Fixing The Plate. When the plate is completely developed, it is rinsed under the tap and then placed directly into the fixing bath. It must remain in this bath until all yellowness entirely disappears from the plate. Where potassium cyanide is used as the fixing agent, bear in mind, as previously stated, that this is a deadly poison. Do not allow it to come in contact with scratches or sores. The bath containing the cyanide should be kept closed, as the fumes from the cyanide are sometimes injurious to the health.
Washing The Plate. After the plate is thoroughly fixed it can either be washed under the tap, by hand, for five or ten minutes, or placed in the regular washing box fifteen to twenty minutes. After washing, the plate is set in the negative rack to dry.
Re-Developing. There are times, when using a newly prepared, or overworked, bath that the image does not develop up as strongly as you would like, with the result that the negative is weak. Such negatives can be improved very materially by re-development.
The Re-Developing Solution. In a small bottle, prepare a 10% solution of nitrate of silver. Acidify this solution with a drop or two of nitric acid, C. P., or sufficient to instantly turn blue litmus paper red. Label this bottle, "Silver Stock Solution for Re-developing."
Applying The Re - Developer. When developing the plate in the ordinary way, and after applying the developer, you find the plate still lacks strength, pour into your tumbler or a graduate, 4 or 5 ounces of your developer. Add to this about 10 drops of your silver re-developing solution to every ounce of developer and flow the plate with this combined developer. This re-developer will considerably increase both detail and density, and should only be used when the image from the first application of developer appears weak and lacking in detail. If, however, the negative is weak but has sufficient detail, intensification is necessary.
Intensifying. Where the plate simply lacks in density, the image may be intensified by either of the following formulae:
923. The first formula is made up of pyrogallic acid and the second of ferrous sulphate. We would recommend the second formula, although very good results can be obtained with either. The pyro intensifier will build up the image much more readily than the iron. This method, therefore, is more suitable for a negative which has been properly exposed, but possibly under-developed. The second formula is best applied on negatives which have been under-exposed, but fully developed.
Formula No. 1.
Formula No. 2.
Ferrous Sulphate ..................
Citric Acid ........................
924. Wash the plate thoroughly and flow the intensifying solution over it in the same manner as you flow the developer over the plate. Constantly rock the plate until you have produced sufficient density, after which it should be washed thoroughly.
925. Intensifying may be done before or after fixing.
If the plate is over-exposed it is advisable to intensify after fixing; if under-exposed, before fixing.