Archived posting to the Leica Users Group, 2005/04/21
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Most of the photographic chemicals in use today are rather benign. The developers are diluted heavily and pose no environmental threat. Developers like Xtol and PCK are Ascorbic Acid-based and probably improve the waste! D76 and the derivatives of that formula contain chemicals that are used in food processing (Sodium Carbonate) and pool cleaning solutions (Sodium Sulphite) and are not dangerous for septic systems and treatment plants. The biggest culprit is the used fixer. The silver dissolved in fixer can cause problems in septic systems and in large quantities also affect treatment plants. Mind you, it takes 80 rolls of 35mm film to get an ounce of silver in your fix so the volumes usually encountered in a private darkroom are not serious. Silver recovery is possible but it is really not feasible unless you are doing commercial volumes. I used to do it by keeping a sealed bucket (with a small vent pipe) with pure steel wool in it. You poured the fixer in the bucket ensuring that the steel wool was always covered by fix. The steel wool attracted the silver molecules and slowly "cleaned" the fix. It is a smelly process so you have to keep the bucket outside and in the end you have a black goo in the bottom that you could bring to a recovery plant. With today's silver price hovering around $5-6/ounce it is not worth it unless you do a couple of 100 rolls of film/month and lots of fiber based prints. There are a couple of developers that are quite "clean". The PCK (unblinkingeye.com), a Patrick Gainer formulation that works very well with Tri-X, Acros, etc. - its main components are Vitamin C (Ascorbic Acid), Phenodine (0,3 grams for 30 rolls), Borax (a naturally occurring alkaline - 20 Mule Team brand from Death Valley) and Sodium Hydroxide (sounds ominous but is a Kodak name for Red Devil Lye). The PCK is diluted 8 times for use so it is virtually exhausted after use. The classic Rodinal contains some not so healthy components but with dilutions ranging from 1:25 to 1:125 in normal use it is again so diluted that it poses no threat. Some of the Pyro formulas are dangerous in concentrated form but once they are in suspension with water the dilutions are so great that they are rendered virtually harmless. If you are a heavy fixer user (5-10 gallons a month) you should probably do the right thing and take the used fix to a collecting place rather than jeopardising your septic tank system. City systems get more "crap" into them than even the most eager darkroom users could amass; oil-drips, leaky radiators, detergents from households, roadsalt after the winter, etc. Keep printing and processing, Tom A --------------------- Tom Abrahamsson Vancouver, BC Canada www.rapidwinder.com