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.
Directions For Use. Take sixteen ounces Stock Solution No. 2, eight ounces Stock Solution, No. 3, and eight ounces Stock Solution, No. 4, making thirty-two ounces of Stock Solution. To this add twice as much water as you have solution, or sixty-four ounces water, making ninety-six ounces of bath. If you have a smaller tank you will require less solution, and if more solution is required to fill your developing tank, increase the quantity, but always keep the proportions the same. This solution will fully develop normal exposures in twenty minutes.
506. Figuring by the factorial method, we find the factor for this developer to be forty, and time for development twenty minutes. We would obtain the factor for this bath in the following manner: We have used sixteen ounces of Pyro Stock Solution, No. 2, containing five grains of pyro to the ounce, the sixteen ounces contain eighty grains. To this sixteen ounces of Pyro Solution, add eight ounces of No. 3, and eight ounces of No. 4, making a total of thirty-two ounces of developer. By adding sixty-four ounces of water to this, making a total of ninety-six ounces of solution, we have diluted this normal bath exactly twice. We now have eighty grains of pyro in the ninety-six ounces of solution, or five-sixths of a grain pyro to the ounce of solution. We found the image on a normally exposed plate to appear in this developer, with the solution at sixty-five degrees Fahr., in thirty seconds, and the development was completed in about twelve hundred seconds, or twenty minutes. The factor for this developer, therefore, is one-thirtieth of twelve hundred, or forty, and a plate developed in this strength bath, and at the same temperature, will develop in twenty minutes. In case of plates being very much over-exposed, in order to obtain the proper snap and contrast between highlights and shadows, you may need carry the developing farther. It may perhaps require twenty-five minutes to produce the proper strength; then, after fixing, if they are a little too heavy, reduce them with red prussiate reducer, according to the formula in Instruction on Reducing. As the red prussiate reduces the highlights and shadows alike, the plate when reduced will be soft, yet have proper contrast between highlights and shadows.
507. Slightly over-exposed plates will develop in the normal time. Under-exposures will usually develop in the same period of time as normal exposures, and ordinarily such exposures will develop better with tank development than by developing in the tray, because the weaker developing solution allows the developing agent to thoroughly penetrate the emulsion, and work up shadow detail, where a very quick acting developer tends to surface development, and the strongest lights have become opaque before the emulsion is sufficiently softened to allow of the required amount of action on the shadows or under-exposed portions. In case of extreme under-exposure a more diluted bath is still better and will produce better results, but will require more time to complete the development.
Proportions for Different Size Tanks. For a forty-eight-ounce tank, use the following: -
.................. 4 ounces.
................. 32 ounces.
For a twenty - four - ounce tank, use : -
508. The temperature of the developer should never be below sixty degrees or higher than seventy degrees Fahr., sixty-five degrees being normal. In some localities the water may be such that you will find it necessary to add more or less water with the same amount of Stock Solution, in order to develop in the given time. This is only in extreme cases, and should it occur, and if the factorial method for tank development is employed, it will not matter whether the water used is strongly alkali or even acid, for the factor for the developer employed remains the same, only the time of appearance is changed, and all that will be required under such conditions is to know the time of appearance, and multiply by the factor, which will give you the exact time required for complete development, and all plates developed with the same water conditions thereafter will be fully developed in the same time. A little experimenting, and carefully keeping a memorandum of your results, will soon enable you to regulate the speed of the developer.