A demonstrator dropped into a studio recently and found the photographer intensifying the entire lot of negatives made and developed the day before. Naturally, the cause of weak negatives interested the demonstrator, for it is his business to keep the materials he demonstrates working up to standard.

On asking the cause of the trouble, the photographer remarked that his developer had not been working as it should and he felt sure the developing agent was not up to standard or the plates were off quality. "I have a few plates to develop this morning," he said, "and you might see them go through."

The demonstrator halted operations long enough to get his thermometer into action, for the dark room was quite cold. As he supposed, the temperature of the developer when ready for use was slightly over 50 when it should have been 65 . Some hot water was placed in a large tray and the developing tray placed in this until the temperature reading was slightly above 65°. By the time the plates were developed the solution had dropped a few points and development was perfectly satisfactory.The tips of your fingers will never take the place of a thermometer. If your hands are very cold, water at 55° will feel 65°.

The wrist is more sensitive than the finger tips, but. why guess when thermometers are so plentiful?

In the case mentioned an unexpected cold snap had so materially reduced the temperature of the water supply that the usual winter precautions had been forgotten.The results of developing at low temperatures are very likely to be encountered in tank development. If small plate tanks are used the developer may be made up and used without the fingers touching the solution or a thermometer being used. The air-tight tank acts, in a measure, as a thermos bottle and holds the temperature fairly even for the time of development. This is an advantage if the solution is at the proper temperature when the plates are placed in the tank, but a thermometer should be used to make sure that the developer is not below 65o, the normal developing temperature.

With large open tanks, maintaining the proper temperature is a more difficult problem. Photographers, as a rule, appreciate the importance of temperature, and in many cases where large tanks are used a water jacket has been built around the tank. This permits one to fill the space between the jacket and the tank with hot water and by so doing, to keep the developer at the normal temperature.

Cold Developer StudioLightMagazine1918 19


By Wm. Berger Germantown, Pa.

If large tanks are not provided with water jackets, a glazed fire brick or a stone may be heated and placed in the tank, or a jug of hot water suspended in the solution until the temperature has been raised to the desired point.

Negatives that are slightly too thin can be improved by drying quickly in a warm room with an electric fan, but it is best to secure the proper density by sufficient development in a solution of the correct temperature. As the rate of drying does have an effect upon density the greatest uniformity is secured by drying all negatives alike with an electric fan in a warm room.

Papers Discontinued We are discontinuing the manufacture of photographic papers included in the following list as other grades in all cases cover the work for which these papers were intended:

Azo Grade A Soft, Single Weight. Azo Grade D Soft, Single Weight. Azo Grade D Soft, Double Weight. Azo Grade B Hard, Single Weight. Artura Chloride Medium Rough. Artura Chloride Heavy Smooth. Bromide Platino A. Platino C.The users of Azo Grade A Soft and D Soft Single Weight and D Soft Double Weight will find that corresponding brands of Hard can readily be substituted.The demand for Artura Chloride Medium Rough is not sufficient to continue its manufacture. As a substitute for Artura Chloride Heavy Smooth, Iris Grade C may be used, as the surface is practically the same.

As a substitute for Platino A Bromide, Matte Enamel can be used and for Platino C, Standard C is a satisfactory substitute.The idea that additional safety is secured in a dark-room by covering the walls and ceiling with a non-actinic color is an old one and one that is very persistent. A little thought should,however,be enough to show any one that the color of the walls makes no difference whatever if the light is safe.

Therefore, if a reliable light is available we may just as well have the walls and ceilings as white as possible and reap the benefit of as much light as possible reflected about the room and in the corners.Assuming the light not to be quite safe, the colored walls may have an advantage, but in fact it is more of a theoretical than a practical one, for the light is so enfeebled by reflections that it is likely to be rendered comparatively safe even if the reflecting surface is white.

Cold Developer StudioLightMagazine1918 21


By E. G. Dunning New York City