From: Sandy King (sanking@clemson.edu)
Date: 12/08/02-06:12:01 PM Z
Richard wrote:
>
>Sandy,
>
>The flaw I see with this procedure is the wash at step 2 and the rinses.
>From some simple experiments with FAC it appears that an alkaline
>wet processing stage forms a low solubility iron compound. Hence
>all wet processing should be neutral/slightly acidic until the iron
>has been removed. I would thus propose:
>
>1. Expose
>2. Citric wash (two stages)
>3. Rinse (The unwanted salts should have been removed in step 2)
>3. Tone
>4. Wash
>5. Fix ...
>
>At this stage I have not looked at how acidic the bath must be remove
>the iron salts, hence a 3% solution may be stronger than required.
>
>
>Richard
>---
>Richard Urmonas
>rurmonas@senet.com.au
>
>-------------------------------------------------
I was thinking on the assumption that a 3% citric acid clearing bath
could remove the soluble iron compounds at any point in the wet
processing procedure. What you are saying is that the soluble iron
compounds are actually changed in some way with any alkaline wet
processing that takes place before the compounds are removed, right?
If so, this would also have implications for regular kallitype
processing as well as VDB and n theory I should eliminate the water
rinse that I have been using between development and the citric acid
clearing bath. This assumes of course that ferric oxalate and ferric
ammonium citrate compounds function alike at this particular stage.
In any event your processing proposal makes sense. However, what
percent solution of citric acid do you propose in step #2?
Sandy King
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