Re: Liquid Emulsion Questions
From: Camden Hardy <camden@hardyphotography.net> Subject: Re: Liquid Emulsion Questions Date: Sat, 23 Sep 2006 12:28:58 -0600 (MDT) > Have you considered using an alternative process like Van Dyke > Brown? Depending on the process, you probably wouldn't need to > worry about disposing the chemistry. Most of the chemistry I use > can be dumped down the drain. In small scale silver-gelatin processing, developer and fixer are the concern for disposal. Phenidone-ascorbate type developers can be readily decomposed in sewer system and environment and it is not a problem in most areas with decent sewer system. Used fixer is a problem because it contains silver (up to 1% in heavily used fixer), which makes sludge in sewer system (when mixed with dirty water from other sources---particularly that smells sulfur) and is burdensome to the sewer treatment plant. Silver is a precious resource and should be recovered anyway, so most institutional users collect exhausted fixer. Switching to printing-out silver processes doesn't really eliminate this problem because silver will be released to the effluence water anyway. Considering the problem of preparing 4' square negative for contact printing with UV light, etc., silver-gelatin process is best suited for large work. One clear advantage of silver-gelatin is photographic speed and enlargeability.
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