From: Katharine Thayer (kthayer@pacifier.com)
Date: 03/18/03-02:19:53 PM Z
Christina Z. Anderson wrote:
>
> I also tested sensitizing the paper, drying, and putting a layer of
> pigment and gum on top (one of Wall's ideas) and it worked--weird. Didn't
> expect it to, thought the layer of top paint would all swoosh off, not
> conceiving how it would intermingle with the layer of dichromate below, but
> it did. Go figure.
> Chris
Chris,
As long as the tooth of the paper is open, (and there's no reason
that, watery as it is, the dichromate would clog up the tooth) the gum
should hang onto the paper, regardless of the dichromate underneath. The
gum and dichromate don't need to be mixed together, only to be in
proximity to each other, for the hardening process to be completed. It
seems maybe counterintuitive that the dichromate could "get out" from
underneath the hardened gum to wash away, but how does the dichromate
"get out" of the hardened gum to wash away when they're mixed together?
One assumes that the hardened gum is permeable enough that the
dichromate can escape either way. John suggested that it's possible that
some of the sizing in the paper could have been hardened by the
dichromate, and that's possible, since paper manufacturers as a rule
don't use a hardener with their gelatin. If the image was the brown
dichromate color, then John's theory wins; if it was the color of the
pigment you put on top, then mine wins, or maybe both.
Katharine
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