As the commercial man is generally working for some special result and nearly always has to control development to a certain extent, I think pyro is by far the best developer for all-round commercial photography. While there are operators who get very rice results with different coal-tar developers, they are generally those who are working on some one line all the time, have their exposure right down to a nicety and their lighting always under full control, but, for the average commercial man, who is meeting any and all conditions, I believe you will find more of them using pyro than almost any other developer and with the straight old A-B-C formula. For my work I use less water than the formula calls for, but I believe I time longer than most operators under the same conditions, and thus arrive at about the same result. As to the advisa bility of using tank development, it is very good for long runs of negatives, such as furniture, stoves and similar lines, but for the average studio work, development seems best handled by tray. Likewise, most panchromatics are developed in tray, excepting those for long runs.
Many people believe that if they had some one formula, the key to success would be theirs. Such is not the case. It is experience with a little brains, mostly brains, that really helps to make success in developing, and to know your product and balance your chemicals to suit it, taking into con sideration your water conditions. I have made negatives in various parts of the country under any and all conditions and have used practically nothing else but pyro developer, almost identical with the formula published, varying my amount of carbonate and sulphite to meet local conditions.
For a stock solution of developer, I have used the following for a number of years on different occasions and like it very much : There are times when you will' need intensification or reduction, sometimes both on the same plate. The kind of reducer to use will be governed somewhat by the kind of negative you have. If your negative is harsh in the high-lights, but fairly good in the shadows, a reducer like the following will be just about what you will want and is known among the commercial photographers as "high-light" reducer : No. 1—Saturated solution of Potassium Permanganate. No. 2—Sulphuric Acid, C.P.
Take about one dram of No. 1 and six or seven drops of No. 2, to ten to twelve ounces of water and you have a pretty nice reducer for that kind of a negative. To use it, the plate should be thoroughly washed first and it is always well to try the reducer on the extreme edge first to get the speed of it on that particular plate. It can be used locally or all over. The way most of the workers use this reducer is to immerse the negative in it, rocking the tray a few times, take the negative out and immediately transfer it to a tray of running water, sousing it up and down a few times. If not reduced enough, repeat, if
it is not going fast enough, add more of your stock, and if it is going too fast, put more water in it. After the negative is reduced enough, it should be put in the hypo bath. The idea of using the-running water is to remove the reducer as quickly as possible, as it oxidizes rapidly and will stain the negative if not washed off quickly. Of course, the reduction can be done locally by applying the reducer with a piece of cotton.
This reducer is used probably more than any other formula and it does not reduce the shadows to any perceptible degree and is a mighty nice, quick and clean working reducer.
Sometimes, under certain conditions, a yellow stain will appear when using this reducer, but by placing it back in the hypo, it should disappear. If not, a weak solution of oxalic acid will remove it.
If by some accident you have developed your negative too much all over, or possibly you may purposely have done it, the negative can be reduced very nicely by what is known as Farmer's reducer, which reduces all over. Of course, your shadows being thinner, reduce faster than the high-lights. This reducer is made by making (No. 1) a saturated solution of Potassium Ferri cyanide (keep in a dark bottle, as light affects it) and (No. 2) a saturated solution of hypo. Use about a drain of No. 1 and a dram of No. 2 with four to eight ounces of water, according to the speed you want. Immerse negative all over, or it can be handled locally the same as the other. After the negative is reduced enough, it should be washed under a tap and placed in the fixing bath for a while.
For intensifying, the following is one of the most satisfactory and exten sively used formula. It is a very old formula and has been used practically as long as dry plates have been on the market.
IX oz. Potassium Iodide.
12 oz. Water.
To this add saturated solution of bichloride of mercury until it will not take up any more. As you add the bichloride of mercury to the iodide solution, it will turn red, a sort of salmon color and will almost immediately clear up.
Keep on adding the saturated solution of bichloride of mercury until it stays red, or in other words clears up very slowly. When it does clear up, add enough water to bring it up to 20 ounces and add 1 ounce of hypo crystals. This intensifier can be applied locally or all over and has the advantage of putting a little color into your negative and can be used repeatedly until ex hausted. Of course, your negative should be washed thoroughly before using. If you want to take the intensification out, all that is needed is to soak the negative in water and then put it into the fixing bath and it will be removed.