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.
327. Tank development is based on the principle that an exposed negative will develop to its full density in a developer of a given strength, and with a given temperature. A long series of experiments have proven that the slow development of a negative will bring out greater detail and a longer range of tones than the rapid development, which is generally effected when the tray method is employed. Apart from this the advantages of the tank for the amateur lies in the fact that there is no handling of the plate during development, so that the liability to scratch the film is avoided, and, also, the necessity for examining the plate by a ruby lamp is obviated. This in itself is quite a point, as many of the cheaper kinds of ruby lamps are apt to fog a rapid plate.
328. The simplest form of tank development is that in which an ordinary grooved glass, wood or fibre hypo box is used. Such boxes can be obtained in all sizes, at most dealers in photographic supplies, and, provided they are perfectly clean interiorly - that is, free from all chemicals that will be harmful to the plates during development - such tanks are fully the equal of the improved metal tanks offered by various manufacturers. These latter metal tanks, however, are designed with reference to their use outside the dark-room, and for a good many this is a distinct advantage. Provided, however, that the amateur has at his disposal a dark-room, the ordinary groove tank first mentioned will make an efficient receptacle for plate development.
Note. When using such a simplified form of tank, care must be taken that the plates are lifted up and down in the developer several times when first inserted into the grooves. This is necessary to cause the removal of air-bells, which are liable to adhere to the film and prevent development at those spots. It is also a good plan to agitate the developer in the tank occasionally during development especially if development is prolonged - say over twenty minutes - for if the developer has been standing some time in the tank the active agents are liable to sink to the bottom, creating a denser image on the film in its lower part.
Eastman Plate Tank. For the amateur who is not provided with a proper dark-room, or who prefers to do most of his work in the light, the various improved forms of plate tanks are recommended. Of these, the most advanced in its methods of tank construction is the Eastman Plate Tank. This tank consists of a metal solution cup, or tank, with tightly fitting cover; a cage or rack for holding twelve plates, or less, during development and fixing, and a simple block guide for loading the plates into the cage.
331. The tank is manipulated as follows: First, take the plate rack from the tank and attach the loading block to it. See Illustration No. 39. With the block attached, proceed to load the rack by sliding the plate through the slot in the block into grooves in the rack. See illustration No. 40. Then move the slotted guide over the next groove and load the next plate, and so on until the plates have been loaded into the plate rack, then remove the loading block. Now fill the tank with the developer and turn the plate rack so that the plates are the long way up, and lower the rack carefully into the solution tank. See Illustration No. 41.
Illustration No. 39.Attaching Loading Block to Plate Rack.
See Paragraph No. 331.
Illustration No. 40.Loading Plates Into Rack.
See Paragraph No. 331
Eastman Plate Tank.
Illustration No. 41.Lowering Rock of Plates.
Into Solution Cup.
See Paragraph No. 331.
Illustration No. 42.Fastening Cover of Solution Cup.
See Paragraph 332.
Eastman Plate Tank.
332. As soon as the plates have been lowered into the developer, the rack should be raised up and down a few times by means of the wire rod; this is done to expel air-bells. Then the tank cover is fastened in place and the time is noted, and the hand on the dial on the front of the tank is set to indicate time when development will be completed. See Illustration No. 42.
333. The development is allowed to continue for say fifteen minutes, the entire tank being reversed end for end four or five times during development, as this allows the developer to act evenly over the plate.
334. After development the solution is washed out of the plates by filling the tank several times with fresh water, after which the fixing bath is poured into the tank. The fixing may be carried on in daylight.