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Testing processing chemicals?


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#1 James Steven Beverly

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Posted 30 November 2008 - 05:19 AM

I've had some dry chemicals for a while now (I think like 2 years) and I wanted to find out if there are any tests I can do to find out how well they are holding up. It's naturally dry here so except for the leaky roof that occasionally flooded the studio floors on the lower level (the chemicals were stored on the upper level) and they weren't exposed to that much moisture so I'm thinking they're fine but I'd like to test them there is some jugs of liquid stuff to, I forget what it is. Do they have anything like photographic chemical litmus paper or that liquid you pour on heroin and it turns blue if it's pure sorta thing or something like that. Thanks-Steve
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#2 Mark Dunn

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Posted 30 November 2008 - 06:28 AM

Dry chemicals keep for years in reasonable conditions- ie. not damp, or hot enough to cause decomposition. If they're in drums or sealed bags, they'll be fine.
As for the liquid, it really does depend what it is. Concentrate will last longer than working strength, fixer longer than dev. As long as fixer still smells acid, I'd be happy with it, but if the developer is anything deeper in colour that a pale brown, it's probably oxidised.
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#3 Paul Bruening

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Posted 30 November 2008 - 01:09 PM

If you can store your developer at a little above 60 degrees it will keep longer. Go below 60 degrees and the chemicals will start falling out of solution. Keep them in a bag that you can push all of the air out of. If you have to keep them in a rigid container, releasing nitrogen into the chamber until all the oxygen is replaced plus a sealing lid keeps oxidization down. Like Mark said, liquid developers are the most perishable. They also have the biggest impact on your film.

Even with all of Kodak's admonishments to maintain the quality of chemicals, we kept our chemicals in the worst conditions, left them in the tanks way, way too long and still got some really fine results back 28 years ago at Ole Miss's color reversal lab. Crazy.
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#4 James Steven Beverly

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Posted 01 December 2008 - 04:14 AM

I think the liquid is fixer, I'll have to check. it DOES get hotter than Hell in the summertime easily over a hundred in July and August then probably in the 50s and below in the winter but not on a regular basis. Hopefully they've still be good. At least I'm encouraged by your Ol' Miss tales so maybe we'll get luck by the time I get out there to pick up that stuff from ya. Hey I may have some help setting up the lab, you wanna come out when we're doin' it and maybe you can process a few things too while you're here. Call me or PM me. I thought you could mix up fixer and developer from dry chemicals, am I wrong? :huh:

Edited by James Steven Beverly, 01 December 2008 - 04:19 AM.

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#5 Charles MacDonald

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Posted 01 December 2008 - 09:17 PM

I think the liquid is fixer, I'll have to check. it DOES get hotter than Hell ...
. I thought you could mix up fixer and developer from dry chemicals, am I wrong? :huh:

The Rapid style of Fixer is generaly supplied as a liquid. I belive it is hard to get ammounium thirosulphite (Sure I got a few letters wrong) to go into solution so they provide it as a liquid. When it goes bad, it has some sulpher come out of the solution so it turns yellow and and starts to smell like sulpher. Dry Plain Hypo is quite stable as a crystal s long as you keep it dry.
Most developers for B&W are supplied as a powder, or a liquid. the weak link in most of them is the deveoping agent itself. (Metol, Phenendone or Hydroquinone) which can turn dark if it can get any air. 40 yaers ago the dry stuff came in a metal can you had to open with a pull tab or sometimes a can opener to keep out the air. These days they use a paper or plastic bag. With a few exceptions like "Rodinol" developers that change colour have gone bad.

I am not sure of the stability of the colour formulas, but it is probaly less than the B&W ones.
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#6 James Steven Beverly

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Posted 01 December 2008 - 10:12 PM

Ammonium Thiosulphate ( I googled, 'cause i can't spell it either) BUT close enough :D
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#7 Brian Pritchard

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Posted 03 December 2008 - 04:14 AM

Ammonium Thiosulphate ( I googled, 'cause i can't spell it either) BUT close enough :D

The easiest way to check fixer is to make up a small quantity and stick a bit of raw stock in it, agitate it about and see how long it takes to clear. Fixing times are usually twice the clearing time. So if you know what the fixing time is for the process you are running you can see if it is any good. Make sure the temperature is near enough as that will affect the fixing time.

You can do a similar thing for B/W developers and stick a bit of raw stock into the developer, agitate it for about the correct development time and make sure the film has gone good and black. You do this in the light.

Brian
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