Re: When to tone?

DEAR LIST,
     A question for the chemists on the list: Please let me know if
what I say below is correct.
     I seem to recall in the distant past (1971?) trying to stay awake
in an 8 am lecture by Dr. James from Kodak, author of THEORY OF THE
PHOTOGRAPHIC PROCESS, discussing Zwitter Ions and the complexity of the
silver-gelatin emulsion. He warned that the combination was so complex
that, if prints were dried when not sufficiently washed (iso-electric
point, and all that jazz) unbreakable links between the gelatin
molecules and pollutants (silver thiosulfate complexes et al) could be
formed. The result would be that they could not be removed with
subsequent washing or washing aids and would negatively impact on the
permanence of the print. It seems that this might offset the
beneficial effects of toning. This seems to imply that one must
proceed with complete fixation AND complete washing before drying even
if one intends to tone and give a subsequent complete wash after
toning.
     Again, I am not certain and I ask the photo-chemists on the list
to please advise...
        CHEERS!
           BOB

----- Original Message -----
From: Ryuji Suzuki <rs@silvergrain.org>
Date: Thursday, November 13, 2003 12:07 pm
Subject: Re: When to tone?

> From: mmatusz@pdq.net
> Subject: Re: When to tone?
> Date: Thu, 13 Nov 2003 08:58:29 -0600 (CST)
>
> > I had the same problem with a home made liquid emulsion. As best
> as I
> > could tell this relates to incomplete washing of thiosulfate.
> Brown stain
> > was always stronger when the emulsion was thicker. I ended up
> washing> prints for a very long time before toning. Perhaps the
> use of a basic
> > fixer (like photographers formulary TF4) instead of standard
> fixer would
> > help. I would also try Mr. Suzuki's suggestion of a basic wash
> (sodium> carbonate solution) after fixing. I know the pain, a
> perfectly good print
> > goes into the toning bath and comes out a disaster.
>
> Like I said in another posting, insufficient fixing is my number one
> suspect. Ammonium thiosulfate fixing bath adjusted for neutral or
> slightly alkaline pH is most effective, and they washes a bit faster
> than regular fixers.
>
> You said "perfectly good print goes into the toning bath and comes out
> a disaster" but I find this a bit deceptive. Because prints that are
> insufficiently fixed (or washed) will deteriorate in the future
> and I
> would throw them away rather than keep or sell. The easiest way to
> figure out if the print is adequately fixed is to tone the print,
> because toner would react with unfixed yellow-white silver halide
> crystals to form dark silver compounds.
>
> --
> Ryuji Suzuki
> "Reality has always had too many heads." (Bob Dylan, Cold Irons
> Bound, 1997)
>
Received on Fri Nov 14 12:12:26 2003