3 ms·

I worked in minilabs back in their last days. We were careful about what could go down the drain and what couldn't, but interestingly I don't think we paid anyt

I worked in minilabs back in their last days. We were careful about what could go down the drain and what couldn't, but interestingly I don't think we paid anything to deal with the waste chemicals. They had to go through a recovery process that could then get dumped down the drain, but the waste actually contained silver (famously intertwined with film chemistry through history), and I think those recovery filters may actually have been provided to the company for free because the revenue came from re-cycling the silver.

GekkePrutser 4y ago
That's only for black and white though, I believe?
- musictubes 4y ago
  Nope. All photographic film and paper processing result in silver ending up in the fixer. B&W films have a much greater concentration of silver than color films do but labs tended to develop so much film and paper that it added up.
- hotpotamus 4y ago
  I never touched black and white professionally except C-41 chromogenic (color film that only renders black and white). I don't have any deep understanding of the chemistry, but what I've been told is that all film contains silver, but in color film all the silver compounds are removed and replaced with dyes or pigments (I don't know the tech here) in their development process. Developing accurate and stable color was the holy grail of film photography and was mostly accomplished by the 90's. My understanding is that the silver chemistry is left in black and white negatives and positives and is extremely stable, which is why photographs from the beginning era of photography can be viewed like the day they were developed provided the substrate was stable and maintained well. For instance, Harvard's observatory has an archive of glass negatives that go back to the 19th century and can still be useful for historical data.
  - GekkePrutser 4y ago
    Thanks, I appreciate the explanation! I wasn't aware of it, I've only hobbied with B/W back in the day because it's so much easier (much less complex chemicals, being able to use red light in the dark room during printing)
musictubes 4y ago
Yup. Once the silver was removed from the blix and things were ph neutral they could be sent down the drain. Safe chemical disposal was (eventually) one of the prime criteria used for formulating photo chemicals.

GekkePrutser 4y ago

That's only for black and white though, I believe?

musictubes 4y ago
Nope. All photographic film and paper processing result in silver ending up in the fixer. B&W films have a much greater concentration of silver than color films do but labs tended to develop so much film and paper that it added up.
hotpotamus 4y ago
I never touched black and white professionally except C-41 chromogenic (color film that only renders black and white). I don't have any deep understanding of the chemistry, but what I've been told is that all film contains silver, but in color film all the silver compounds are removed and replaced with dyes or pigments (I don't know the tech here) in their development process. Developing accurate and stable color was the holy grail of film photography and was mostly accomplished by the 90's. My understanding is that the silver chemistry is left in black and white negatives and positives and is extremely stable, which is why photographs from the beginning era of photography can be viewed like the day they were developed provided the substrate was stable and maintained well. For instance, Harvard's observatory has an archive of glass negatives that go back to the 19th century and can still be useful for historical data.
- GekkePrutser 4y ago
  Thanks, I appreciate the explanation! I wasn't aware of it, I've only hobbied with B/W back in the day because it's so much easier (much less complex chemicals, being able to use red light in the dark room during printing)

musictubes 4y ago

Yup. Once the silver was removed from the blix and things were ph neutral they could be sent down the drain. Safe chemical disposal was (eventually) one of the prime criteria used for formulating photo chemicals.