[pure-silver] Re: Chemical Fogging in Reversal Processing
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 16 Aug 2006 11:10:31 -0400
The thiourea or sulfide bath acts like a fogging redeveloper and a
separate fogging bath or re-exposure to light is not required. The only
downside to this method is that the image produced is sepia rather than
black. For black images you need to use a fogging bath or re-exposure
along with a second developer like Dektol.
Jerry
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of John Banister
Sent: Wednesday, August 16, 2006 10:38 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Chemical Fogging in Reversal Processing
> Thiourea is probably being used as a redeveloper in place of
sulfide. The
> result is a sepia image of sulfide. Because either Thiourea or
Sulfide works
> directly on the halide it does not need a fogging exposure or
chemical fogging.
> It also eliminates the need for a final fixing step because all of
the halide
> is converted to sulfide whereas there is always a small residual of
halide > which is not made developable by flashing. I am uncertain
about
the effect of a
> chemical fogging agent but would guess its the same as the use of
Sulfide, that
> is, no final fixing step is necessary.
>
> --
> Richard Knoppow
> dickburk@xxxxxxxxxxxxx
> Los Angeles, CA, USA
Is this situation with Thiourea/Sulfide unique, or do you think it's
more generally true that if a toned result is desired from a B&W
reversal image that the fogging - second development steps can be
bypassed or would likely be easy to incorporate in the toning process?
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