564 HANDBOOK OF PHOTOGRAPHY 



It is easier to warm the darkroom than to cool it. Warm air may be taken from 

 surrounding rooms; or electric, gas, or hot-water heaters maj^ be utilized. Open 

 flame is dangerous particularly if much nitrate film is used. It must be remembered 

 that warm air and water rises and that, if the darkroom is on the same level as the 

 furnace or heat supply, it may be difficult to force heat into the room. 



Refrigerating systems are available for the commercial plants. The best com- 

 mercial plants are not only heated but air conditioned. Suitable equipment is 

 described by Crabtree and Matthews.^ 



If miniature camera negatives are to be processed or if color photography is to be 

 done, certain other requirements must be met. Miniature negatives are frequently 

 enlarged as much as ten to twenty times or even greater. The slightest flaw on the 

 negative, such as scratches, dust spots, or finger marks, are enlarged to the same 

 extent as the desired image and often form the practical limit of successful enlargement. 

 Negatives marred by scratches or with dust or lint will produce prints which 

 may require considerable time and labor in spotting. 



It is necessary, therefore, that the darkroom worker who is responsible for minia- 

 ture film processing take extreme precautions to deliver clean negatives to the printer; 

 the printer also must work in a clean and not too dry atmosphere. Greatest trouble in 

 enlarging miniature negatives occurs on cool dry days when it may become practically 

 impossible to place the negative in the enlarger without getting it covered with dust 

 or lint floating about in the air. 



Air coming into the miniature processing room should be cleaned if possible, and 

 if the room itself can be maintained slightly humid, dust troubles will be lessened. 



Certain color processes may require rooms of given temperature range and of given 

 humidity. These requirements practically force the photographer to install air- 

 conditioning equipment. 



Water and Drain. — Hot and cold nmning water are essential. Hot water is 

 necessary for carbro and wash-off color printing and for certain print toning operations. 

 It is useful in maintaining solutions at temperatures above the ambient. Cold water, 

 of course, is absolutely essential. 



There must be a drain to the sink. This makes it necessary for the darkroom to 

 be above the level of the drain pipes in the building, or it will be necessary to provide 

 a separate drain for waste water and solutions. One expedient is to place a large 

 metal tank, e.g., an oil barrel, in the ground below the darkroom level. If the tank 

 is equipped with pipes or vents running into the surrounding earth — from which there 

 must be good drainage — it will serve as an adequate disposal arrangement. Such a 

 ^\■aste disposal device may be against the sanitary laws of the community, however.^ 



Several faucets should be provided, or other arrangements should be made so that 

 the water may be utilized at various positions. Most city water is dirty and is con- 

 taminated with organic matter and iron rust from pipes. The water, therefore, should 

 be filtered before mixing solutions or washing films. This can be done by tjdng several 

 layers of cheesecloth over the end of a hose attached to the faucet; or by running the 

 water through felt. Commercial filters for this purpose are available. 



It will be an advantage if the floor is smoothlj^ cemented, sloping to a drain in the 

 center. Over the cement may be placed boards which may be removed occasionally 



1 " Photographic Chemicals and Solutions," Am. Photographic Pub. (1939). A considerable 

 quantity of valuable data will be found in " Motion Picture Laboratory Practice," Eastman Kodak Co. 

 (1936). 



- The author has used a .50-gal. tank of this type in a small color laboratory for over a year. The 

 quantity of waste water at any one time is not very great and on Long Island, where the darkroom is 

 located, the soil is sand and glaciated gravel having good drainage. It is necessary to have an air vent 

 in such a tank, however, or water will not run into it. 



