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.
Alteration Of Formula For Different Brands Of Plates. The formula for developing given herein will work well with any brand of plate by following the above directions. If you are using a brand of plate that will strengthen quickly use more water. If, on the contrary, you cannot get the desired strength, reduce the amount of water, thus making your developer stronger and the developing agent (pyro) will act more rapidly.
56. For Seed, Standard and Stanley Plates use according to formula; for Cramer (more pyro should be used) ten drams of the Pyro Stock Solution No. 1 and nine ounces of water; but for Hammer Plates (use less pyro) only six drams of Pyro Stock Solution No. 1 and eight ounces of water. Sodas remaining the same for all brands of plates.
Fixing Bath. For fixing bath use plain hypo and water, one pound of hypo to two quarts of water, or testing sixty by hydrometer, and during hot weather keep the bath cool. Allow the plates to remain in this bath about twenty minutes, or about ten minutes after all whiteness (bromide of silver) has disappeared. Should plates show a tendency to frill in hot weather, prepare a hardening bath composed of one-half ounce of ground alum to one pint of water. Immediately after fixing, rinse the plates well and then immerse them in this hardening bath for one minute, or until the film becomes hardened, and transfer them to the washing box. The hypo bath will discolor after using a few times, but this need not alarm you, as the hypo bath is good as long as it will fix plates in a reasonable length of time, say fifteen minutes, and not stain them. Always rinse your plates carefully before placing them in the hypo; otherwise you will be carrying the developer into the hypo, and this is what causes the discoloration.
58. We advise the use of the best sodas. Do not buy the commercial goods. Pure crystals, or anhydrous sodas are the best.
Weights And Measures. When not using the hydrometer in making up your solutions, the Apothecaries' Weight and measures should be used.
20 grains - one scruple
......... 20 grains
3 scruples - one dram
......... 60 grains
12 ounces - one pound
......... 480 grains
12 ounces - one pound .........
......... 5760 grains
............. one fluid dram
.... one fluid ounce
............. one pint
............. one gallon
Preserving The Pyro. The Pyro Stock Solution should be kept in a tightly corked bottle, using a glass stopper (if possible, a brown or yellow bottle preferred). If a plain glass bottle is used, wrap it with dark paper, and place in a dark, cool place in your dark room. It should be shaken each day to keep the sulphuric acid thoroughly mixed with the pyro and water.
61. The formula given herein for developing can be adjusted to any class of exposure. By diluting with water for under-exposure, and by carrying farther in the normal developer for over-exposure, you have control of the plate under all reasonable conditions.