From: Liam Lawless (liam.lawless@blueyonder.co.uk)
Date: 12/08/02-01:14:54 PM Z
Sandy,
Sorry, I do not tone very often and was thinking about the big "pop" when an
untoned print hits the fixer. This, I think, might be lost. However, if
this does not occur with toned prints, and *IF* it is something to do with
iron (as it is with trad. Pt/Pd), then maybe toning "locks up" the iron in
some way that could make clearing ineffective.
Liam
-----Original Message-----
From: Sandy King [mailto:sanking@clemson.edu]
Sent: 08 December 2002 18:45
To: alt-photo-process-l@sask.usask.ca
Subject: RE: VDB test results: related concerns
Liam,
I am not sure that the premise of your question is correct. When one
tones a VDB print the image, whatever it is (silver, or gold,
platinum or palladium plated silver?), is fully produced. Placing it
in the hypo does not change the appearance in the least. This being
the case, as I at least have observed, what advantage do you see in
clearing after fixing?
Sandy
>Sandy,
>
>If image silver is produced by "solubilising" the iron with hypo, then
>wouldn't the clearing stage would be better following the fix?
>
>
>
>Liam
>
>-----Original Message-----
>From: Sandy King [mailto:sanking@clemson.edu]
>Sent: 08 December 2002 17:32
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: VDB test results: related concerns
>
>
>Ed Buffaloe wrote:
>
>
>>3% citric acid might be too strong for VDB. After 2 minutes each in 6
>>successive trays of water with only a pinch of citric acid, I find that my
>>VDB has become visibly less dense. Of course, it seems to gain much of it
>>back in the fix...
>
>
>
>I would expect some loss of density because acid bleaches the silver.
>However, if the clearing baths are used after toning with gold,
>platinum or palladium it is possible that there would be no fade back.
>
>What I would propose as an alternative VDB processing procedure for
>maximum image permanence would be this:
>
>
>1. Expose the print.
>
>2. Wash for a couple of minutes to get rid of most of the soluble
>silver halides.
>
>2. Tone.
>
>3. Brief rinse.
>
>3. 2 minutes in clearing bath #1 = 3% citric acid.
>
>4. Brief rinse.
>
>4. 2 minutes in clearing bath #2 = 3% citric acid.
>
>5. Brief rinse.
>
>5. 2 minutes in fixing bath #1 = 5% sodium thiosulfate
>
>6. Brief rinse.
>
>6. 2 minutes in fixing bath ##2 = 5% sodium thiosulfate
>
>6. Brief rinse.
>
>7. 2 minutes in 1% sodium sulfite solution.
>
>8. Final wash of 30 minutes
>
>This is obviously a much more complicated procedure than what is
>normally used for VDB but in theory it should establish the acidic
>conditions that would assure maximum elimination of residual iron
>salts. Is this necessary to get image permanence? I don't know.
>Richard Knoppow has provided information on how to test for residual
>silver salts. Does anyone know how to test for residual iron salts?
>
>
>
>Sandy King
>
>
>
>
>>
>>>
>>> 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
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