Re: Shelf Life for Photopolymer plates
- --- In PPLetterpress@yahoogroups.com, "Gerald Lange" <Bieler@...> wrote:
>I'm not asking for absolute permanence; we are all doomed in the long run. But I'd like production materials to last until I decide to discard them.
> I am not sure what you mean by permanent. How long is that? To the end of time?
I've been looking recently at some of my father's continuous tone negatives, going back to the 1930s. The silver emulsion is still fine, even when the carrier is not pristine. I installed a process camera in 1984, and still have tray-processed lith negs from that time that are unchanged. (It's only with rapid access film processing that the production environment assumes short life for the end product, with a very short fix and no need for a 10 or 20 minute wash.) I've made plates from 20-year old negs. I have also held negs more than six months before the job ever went to plate, so it looks like care will be needed with new outside negs.
However, silver is a real pollutant if not recovered from the spent fix; it kills the helpful bacteria at the sewage plant. But the amount of illegally-disposed fix must be a fraction of what it was 10 years ago, due to technological changes, so it's hard to imagine any political pressure for reformualtion. Hell, I bet illegally-disposed inkjet cartridges outweigh fix by far.
--Eric Holub, SF