[pure-silver] Re: Chemical Fogging in Reversal Processing

  • From: John Banister <jbanister@xxxxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Wed, 16 Aug 2006 10:37:46 -0400

> 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?


=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your 
account (the same e-mail address and password you set-up when you subscribed,) 
and unsubscribe from there.

Other related posts: