[pure-silver] Re: Fixing after indirect toning - a deeper question
- From: "Tim Rudman" <tim@xxxxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sat, 14 Jan 2006 09:28:58 -0000
<< Some, but not all, indirect toners leave some silver
_halide_ behind after toning.>> (Richard)
This is particularly true of many of the metal ferrocyanide toners. It has
been estimated that only about 75% of the silver halide is converted to the
non-silver metal with iron and copper toning. For this reason post-toning
fixing is sometimes used after these toners to brighten the colour &/or to
minimize colour change from sulphuration.
(E.G: Quote from my Toning book: In addition to this, not all the
image-silver is converted to ferric ferrocyanide in the toning process. A
quarter of it is converted to the nearly colourless silver ferrocyanide and
this is very susceptible to turning brown from sulphuration by atmospheric
pollutants. If this is fixed away by a weak acid fix after toning, the
colour will shift a little, but the image should be much more stable.)
I wasn't sure from your post Chris, whether you were asking only about
sepia?
Tim
http://www.worldbookoflithprinting.com
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Knoppow
Sent: 13 January 2006 23:15
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Fixing after indirect toning - a deeper question
----- Original Message -----
From: "Christopher Woodhouse" <chris.woodhouse@xxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, January 12, 2006 1:15 PM
Subject: [pure-silver] Fixing after indirect toning - a deeper question
>I have read the recommendation that fixing after indirect toning
>removes and untoned silver from the print. Whilst I know that during
>the toning step, there is a clear build up of image tone and colour
>change over a few minutes, suggesting that if one pulls a print
>early, some of the bleached silver will remain untoned. So far so
>good.
>
>
> But... Is it being suggested that longer toning, say 5
> minutes with
> agitation, of a bleached print still leaves behind
> residual bleached silver?
> In the back of my mind I know toner will quickly detect
> incomplete fixing
> and even show up poor washing too, discolouring the paper
> wherever there are
> reactive silver complexes....so why should toner at the
> same time be so poor
> at converting the bleached silver back into silver
> sulphide?
> --
> Regards Chris Woodhouse ARPS (All Real Photos use
> Silver)
>
Some, but not all, indirect toners leave some silver
_halide_ behind after toning. The final fixing step is to
remove this halide which otherwise will have the same effect
as incompletely fixing of an untoned image. The halide will
eventually decompose causing staining. In the case of an
untoned image the decomposing halide will also attack the
silver but may have less effect on the silver sulfide of a
toned image.
A final fixing step is absolutely required for Nelson's
Gold Toner but probably not for hypo-alum type toners. Often
the fixing step recommended after hypo-alum is mainly to
harden the emulsion after exposure to the relatively high pH
and high temperatures of the toning bath.
Note that a fixing bath does not dissolve metallic
silver, only silver halide (very extended fixing, especially
in acid ammonium thiosulfate fixers _do_ remove some
metallic silver).
Some toners will tone halide as readily as metallic
silver so well fixed prints are a necessity. The standard
test for fixing is a 2% solution of Sodium Sulfide, about
the same as the redevelopment bath of indirect Sepia toner.
A polysulfide toner like Kodak Brown Toner will also tone
halide resulting in a stain if the print is not well fixed.
Of course, an indirect (bleach and redevelop) toner will do
the same thing.
Not all toners require extensive washing before toning.
Hypo-Alum-Sepia toner in particular requires only a short
rinse.
Kodak Rapid Selenium Toner also tones halide and, in the
past, was suggested by Kodak as an alternative to sulfide as
a test for fixing (at 1:9 dilution). It fails where there is
too much hypo in the emulsion so must be used only on well
washed materials.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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