From: Etienne Garbaux (photographeur@softhome.net)
Date: 10/30/03-05:59:09 PM Z
Sandy wrote:
> What I gather from this test is that a palladium toned kallitype
> should have great permanence since virtually all of the silver has
> been replaced with palladium. However, since a very small percentage
> of the silver remains in the print I will continue to call my prints
> of this type as palladium toned silver-iron prints, not just
> palladiums, even though for all practical purposes they are *almost*
> that.
Sandy,
The small density drop that you observed may not imply a similarly small
silver content in the toned image. Depending on the geometric
(topographic?) distribution of the two metals in the image grains, a very
small amount of Pt (or Pd) could conceivably retain much of the original
image density. It's also possible that the bleaching time required to
fully bleach an untoned print is insufficient to bleach all of the silver
out of a heavily toned print, because the toning may protect the silver to
some extent. Based on my hypothesis that post-toning silver content is
roughly proportional to the original silver grain size and my belief that
kallitype grains are larger than salt print grains, I'd be surprised if the
actual silver content of a toned kallitype is less than 25-30%.
Best regards,
etienne
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