The effect of light values in the studio as pertaining to correct tank developing.

1909 Addition.

To insure the best possible results by this system of development, many principles must be closely adhered to which are frequently overlooked or, at least, neglected. The most important considerations are temperature, strength of chemicals, and the chemical properties of the light used in making the exposure and their relation to the proper time of development. The writer's experience has been that when the light used in making the exposure is in large volume its effect in the development is equivalent to that produced by an alkali, and there is an excess of detail and slower building power. Under such conditions of light the best results are obtained when the quantity of stock chemicals used are doubled and the time of development necessary in obtaining proper density is reduced, when much more brilliancy will be obtained. On the other hand, when the light is narrow and used more concentrated rather than in large volume the same relation of balance does not exist between high-lights and shadows, and the slower action of the chemicals (resulting from a more diluted solution, which requires longer time for development) usually gives best results.

From the above it will be seen readily that in addition to time and temperature due attention must also be given to the light conditions under which the exposures are made. Thus, the more closely the individual problem of the photographer is adhered to, and conditions of chemicals, temperature, chemical properties of light and its effect upon the time it will take with a given strength of chemicals to obtain the proper density, just so satisfactorily will results be obtained.

The fact that in one studio where a large volume of light is employed when making the exposure, a developer (prepared with two ounces each of the different stock solutions with a given amount of water added, and the temperature of the solution of 65° Fahr.) should develop in twenty minutes and give excellent results does not mean that the same results would be obtained under different conditions in another studio where a more concentrated or a different actinic value of light was employed in making the exposure. Due to the different chemical properties of light, the same conditions may require 25 to 30 minutes to secure the same quality; so the most careful adaptation to the individual conditions under which one is working yields unquestionably the best results.

Developing Tanks for the Professional - The professional photographer, as a rule, seeks the easiest and simplest methods possible for accomplishing results; therefore, many of them who have adopted tank development employ the regulation rubber fixing tank, with a tight fitting cover, which, if properly handled, answers every purpose. The principal objection to this tank is the possibility of streaks and air-bells. This objection may be overcome, however, by raising and lowering each plate when first placing it in the tank, and then occasionally shaking the latter gently to mix the solution thoroughly.

The regular rubber hypo tank method can be improved

Tank Developing for the Professional

224c upon by providing a wooden box, made three inches larger each way than your regular hypo tank, painted both inside and outside with shellac, or black mogul varnish, making the box water tight. Then provide a grooved box, similar to the rubber hypo tank, minus the bottom; in other words, provide a rack or cage, properly grooved, into which you can place your plates for developing. Should you have an old rubber hypo tank, which is discarded on account of its being cracked or broken in some particular place, making it unfit for use, take this tank and cut out the bottom to within a half inch of the side walls, and also cut the rim off the top of the rubber tank, thus making of it a cage or rack for holding the plates.

The developer is placed in the large wooden tank, and when ready to develop the rubber rack, or whatever rack you provide for this purpose, is filled with plates and gradually lowered into the developer, and the rack loaded with plates is raised up and down a few times in the solution, to eliminate any air-bells that might collect. With this done the tight fitting cover is placed on the tank and the time taken. After the plates have developed, say for five minutes, the cover is removed and the cage containing the plates is turned on its side., The cover is again put on for another five minutes, when the cage is turned on the other side. In this way even development is obtained. After development the cage may be placed in a hypo tank, made the same as the developing tank, and when fixed the plates may be washed in the usual way.

Note. Should the cage be made of galvanized iron, then the plates must be removed from the cage and fixed in a separate hypo tank, as it would not do to place a galvanized iron rack in hypo. Rubber or nickled - brass cages may be used for both developing and fixing.

Developers. - Any of the formulae given in this volume for Tank Development will give satisfactory results. First determine upon the results desired, and then prepare the formula to produce such results. For example, where softness is desired pyro - metol makes a good combination, for the metol assists in producing detail when one is inclined to under-time. The following formula for acetone - pyro developer, suggested by the Cramer Dry Plate Company, has proven very satisfactory:

For tank development take 3 ozs. of each of the above solutions, and add 70 ozs. of water at 70° Fahr. A developer made up according to this formula will develop plates to full density in 30 minutes.

If the pyro - acetone is desired for tray developing take 1 02. each of 1,2 and 3 to 5 ozs. of water.

Note: Observe that the acetone is mixed separately from the pyro or sulphite of soda. It has been found, by experience, that these chemicals are more active when prepared in stock solutions separately and mixed together when ready for use. The advantage of the acetone over the carbonate of soda lies in the fact that plates developed with pyro - acetone will not streak nor develop unevenly in the tank, and it also prevents fog, as plates may be developed with acetone for any length of time without chemical fog. The acetone also prevents frilling, and in case of very short exposures a warmer solution may be employed to good advantage, without danger of frilling or chemical fog. It will be important to remember that when acetone is used in the developer in place of soda, the temperature must not be below 65°, for if worked at a lower temperature the acetone becomes inactive. The experience of the writer has demonstrated that at 70° Fahr. the acetone works at its best.

Tank Developing for the Professional.

224e

Developing Short Exposures. - Since the inauguration of the tank method of developing, which is especially commendable for under-exposures, photographers are becoming somewhat careless in their timing, and are inclined to underexpose most of their work. Owing to this fact the small addition of metol has been added to the pyro formula, which assists in getting out more detail in plates of short exposure. Where full time is given, if one so desires, the metol may be omitted entirely and the formula used as given (minus the metol). Metol has a tendency to give flatness when used on plates fully timed, or but slightly over - exposed; therefore, when one is accustomed to giving full time it is advisable to omit the metol from the formula.

Fixing Bath. - While the plain fixing bath prepared with water and hypo may be successfully employed, yet we find in certain localities, which are troubled with organic substances in the water used, causing spots and stains on the film, that the following chrome alum bath has been found more satisfactory:

Dissolve thoroughly in order given and add No. 2 to No. 1, stirring while adding.

Note. The above bath is intended for hot climates or summer months; for cold climates or winter months use half the quantity of No. 2.

Removing Organic Stains. - While the above bath will prevent any stains of an organic nature, should you have some plates so stained previous to using the above bath, these stains may be removed by first immersing the plate in water for, say, ten minutes, and then flowing over the surface a strong solution of citric acid. This will remove all stains and any excess color from the plate.