[pure-silver] Re: mottled tones
----- Original Message ----- From: "Janet Cull" <jcull@xxxxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, July 13, 2007 12:32 PM
Subject: [pure-silver] mottled tones
I have lots of paper I bought from a man who switched to digital. Most of it has been good. It was all frozen until I bought it. Some has been obviously bad, with very grayish/mottled tones. It looks a bit funky, sort of cool for some things.
I just took some out to use, printing for a friend's kids. These few prints, so far, look good in the white edges (they're perfectly white), good in every part of the print, except for the girl's skin. In real life she has gorgeous, creamy skin. She's young and unblemished.
Is it possible that if the paper is bad from age that it would only show up in certain places or tones? Her blouse is light, but looks fine. The dog's face is beautifully sharp and contrasty to taste, but the girls face is mildly mottled.
I'm using fresh developer. Hm. I didn't change my stop bath but it still looked yellow as if fresh from mixing last night. Fixer is good.
I'm really hoping the paper's fine. I've got too much to feel good about doing away with. 

Thanks!

Janet
I agree with Claudio to check the negative first. Actually, any mottling that is obvious should show up on the negative visually. It is possible some moisture got into the packages of paper and condensed on the surfaces when refrigerated. There may also be other mechanisms at work. Part of the emulsion making process is a step called ripening where the emulsion is aged a little and changes occur to the silver halide particles. Chemicals are added to the emulsion to stop this process before its coated but some ripening continues slowly. The result can be fogging. Although this is usually an overall, uniform, fog, it may also show up as mottling. Where there is overall fog the paper can often be salvaged by adding an anti-fogging agent to the developer. Just plain Potassium bromide will often work but Benzotriazole is more effective and affects paper speed less. Grant Haist has a chart of amounts in his book but I don't have it handy at the moment. I don't know if an anti-foggant is effective on mottling. It also will not bring back paper whose contrast has dropped, another effect of aging. The idea of freezing materials is that most (maybe all) chemical reactions become slower as the temperature is lowered. So, presumably, the fogging action of changes in the emulsion are slowed or stopped. The danger is moisture since, as the temperature is lowered the relative humidity in the container is raised until, at some point, the moisture will condense. Most films and papers are packaged in such a way as to prevent this but it may not always be effective. Packages that have been opened and resealed are much more vulnerable than factory sealed packages. 
  Have you any idea how old the paper is?

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx

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