From: Sandy King (sanking@clemson.edu)
Date: 12/07/02-07:31:26 PM Z
Ed Buffaloe wrote:
>Wynn White writes in his article on VDB: "Most sources state that Vandyke
>prints can be cleared in plain water. In Mike Ware's description of the the
>argyrotype process (http://www.mikeware.demon.co.uk/argy.html) he explains
>the problems iron-based silver processes have. If processed in an alkaline
>solution residual ferric iron is left in the print which will eventually
>cause it to fade since iron (III) will oxidize silver. After reading this I
>decided to change my personal clearing procedure. Since my tap water is
>quite alkaline at a pH of about 8 I feel that there is a danger of insoluble
>iron being left in the print after a conventional wash. To avoid this
>problem rather than use running tap water to clear Vandykes I run them
>through a series trays that have been filled with water to which I have
>added a pinch of citric acid so that the pH falls just below 7."
>
>I have always followed Wynn's advice and have never had problems with
>fogging of my VDB's.
This is an interesting observation, and one that could explain why
with similar processing my VDB prints fog when exposed to strong UV
light, while kallitypes do not. The primary difference in my
processing procedures is that the kallitypes go through two separate
clearing baths of 3% citric acid, a step that is omitted in
processing VDB. If this difference alone explains the fog then it
would appear to result from residual ferric oxalate, not residual
silver salts.
Two questions. First, I wonder what would happen if one followed Ed's
clearing procedure but carried it out in the conditions I described,
afternoon shade where there would be still a lot of UV light. Second,
has anyone tried to process VDB using Kallitype clearing procedures?
I suspect that the use of a citric acid clearing bath before fixing
would bleach the image quite a bit, but perhaps if the clearing was
used after toning there would be no bleaching?
Sandy
>
>----- Original Message -----
>From: "Sandy King" <sanking@clemson.edu>
>To: <alt-photo-process-l@sask.usask.ca>
>Sent: Saturday, December 07, 2002 3:14 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
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