From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 12/07/02-03:53:44 PM Z
----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, December 07, 2002 1:14 PM
Subject: RE: VDB test results: related concerns
>
> I have a further concern about VDB that results from the
processing
> of very large prints. When I make such prints my practice
is to make
> them in the darkroom but for reasons of space wash them
outside. The
> washing usually takes place in the afternoons when the sun
is still
> up, in the shade on the deck. Even after processing that
includes
> toning, two separate fixing baths, and a final bath of 1%
sodium
> sulfite, VDB prints will develop very noticeable fogging
when the
> wash takes place outside, even in very low light. I am
wondering if
> in spite of all of the processing care there are not still
some
> soluble salts left in the paper? If so this suggests the
need for a
> very long wash, even if using hypo clear or sodium sulfite
clearing
> baths. I thought at first that the fogging might be due to
something
> else in the paper other than silver salts but the fogging
only takes
> place in the areas that have been brushed with the
sensitizer.
>
> BTW, the fogging does not take place with kallitype
processed
> following the same procedures.
>
> Sandy King
>
Snipping...
A test of Sodium sulfide or Kodak Rapid Selenium Toner 1:9
as used for silver-gelatin should show up any unfixed
halides. Treat either a scrap or a clear border. There
should be no stain. Either the sulfide test solution or
Selenium toner will tone halide as readily as metallic
silver. This should work on VDB as well as conventional
prints.
It may be that the halide is bound up in the paper fibers,
just as hypo becomes bound in the support of silver-gelatin
paper, requiring a long wash to get it out even with the use
of wash aid.
--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
This archive was generated by hypermail 2.1.5 : 01/31/03-09:31:25 AM Z CST