From: Katharine Thayer (kthayer@pacifier.com)
Date: 05/10/01-04:07:33 AM Z
Katharine Thayer wrote:
>
Some chemist on the list said once, as I recall, that it is
> the result of overexposure, and the dichromate compound actually changes
> to chromium oxide,
It turns out that I read this about chromium oxide in Luis Nadeau's
book, rather than on the list, and to be accurate I should say he
doesn't say it's due to overexposure, only that it is observed "in some
cases, especially with long printing times." I do know that the
assumptions that this chromium oxide "stain" is present (1)in all gum
prints, or (2)in all gum prints made using ammonium dichromate, are both
incorrect.
Katharine Thayer
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