RE: p/p EDTA/ACID

auerbach (auer@AZStarNet.com)
Sun, 25 Aug 1996 16:58:21 -0700 (MST)

>Terry King said on 25 Sunday:
>
>>Certainly there is a distinct difference in sharpness between pl/pd
>prints
>cleared in HCl and those cleared in EDTA even when they have both
>been washed
>over night.
>
>Could you please explain! Which is "sharper"? I use 4% phosphoric
>acid and have cleared prints upon occasion for a couple of hours and
>have not noticed any difference between those that were cleared for 8
>min. Any info would be appreciated.
>
>Thanks,
>John Roseborough

On the subject of clearing with EDTA or Phosphoric acid, why on earth would you
want to clear it overnight! My experience with both agents is that you
want to clear the print efficiently and get it out of the soup! The longer
you soak papers, or at least Cranes platinotype and Ecru papers, the more
chance that there will be some sorts of delamination of the paper. Where
a small bubble or blister will lift.

I would think, though I am not a scientist nor papermaker, that long term
clearing with both EDTA and acid would have a deleterious effect on paper
strength quality. I have noticed that long term clearing of a print made
predominately of palladium in EDTA or Phos. acid will bleach (reduce) the print.

>Gary Auerbach
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