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.
Stock Solution No. 3. Carbonate Soda (hydrometer test 40).
371. To develop take one ounce of No. 1, one ounce of No. 2, and ten to twelve drops (no more) of No. 3, and add twelve ounces of water.
372. Before beginning to develop let us consider again the nature and objects of each chemical used in developing. Stock Solution No. 1 is your pyro solution, or (developing agent) strength producing agent. Stock Solution No. 2, sulphite soda, is your color regulating chemical. Stock Solution No. 3, carbonate of soda, is your detail - producing chemical.
373. In ordinary developing if you desire more contrast you would increase your pyro, because pyro being your developing agent gives you strength, builds up your highlights. If your plate developed yellow in color, you would increase your sulphite of soda in order to retain the proper color. If your plate lacked detail, and developed too contrasty, you would add carbonate of soda, because it opens the pores of the film and permits the pyro to get to the shadows, and, therefore, is your detail-producing chemical. For this method of developing we have provided by prolonged exposure all the necessary detail, so all we require is to retain this detail and produce the proper strength: It is absolutely impossible to develop a plate without at least some alkali, or detail-producing chemical. It requires but a very small amount of carbonate of soda, yet some of this chemical must be used, or the pyro will not attack, and the plate will not develop.
374. Ordinarily, we would desire to have the pores of the film open up as it were, by means of carbonate of soda, thus permitting the pyro to act and build up, and supply the strength necessary. In this case, however, we do not desire the pores to be open, as we are already supplied with the detail by the exposure; therefore, we use only a few drops of the detail - producing chemical, merely sufficient to allow the pyro to develop the plate. The development will be gradual, and the shadows and highlights will build up gradually in their proper proportions, the plate remaining clear and crisp throughout the development.
375. When first placing the plate in this solution, it may require some three or four minutes before the image will appear. If it does not appear by this time, add three to five drops more of the carbonate of soda, or Solution No. 3, These additional drops of alkali will start the plate developing quite freely. After a few more minutes add a few drops more of No. 3, and again from time to time, if necessary, until the plate is fully developed.
376, You must bear in mind that you have added so little of this solution that the pores of the film are not filled with the carbonate of soda, none of your lights or shadows are clogged or choked; your plate is clear throughout, and your developing has been deeper and more solid, and, therefore, is really developed farther than if it were developed in the ordinary way,
377 .Should you find after developing for some time that the plate is apparently fully developed with good, clear detail in the shadows, yet lacking snap in the highest lights, and continuous developing does not seem to build them up, then pour off this solution and make up a normal developer according to regular formula for universal developer. (See paragraph 328.)
378. Immerse the plate in this normal developer for only a moment, examining very closely, for in the normal developer the plate will build up very rapidly. When you secure the proper strength which should not require more than a minute or two at the most, rinse the plate in plain water, and finally fix in a plain hypo bath free from other chemicals.
379. As the developing of the plate by this method is quite slow, requiring fifteen to twenty-five minutes, avoid undue exposure to the ruby light, as you are apt to fog the plate by long development in too strong a light. It is advisable to cover the tray during development and only uncover when you wish to examine it. These precautions must be taken in order to insure perfect success With care and patience the most beautiful results can be obtained.