In a message dated 6/4/06 6:05:27 am, photographeur@nerdshack.com writes:
> My guess is that whatever dichromate gradient might be found will not be
> sufficient to explain the apparent lack of "top-down" hardening in gum
> printing.
> 
Top down hardening occurs in gum printing just as it does in carbon printing.
The aberration of dichromate adhering to the paper results from mixtures used 
being so thin, with such a preponderance   of dichromate solution, that the 
paper is contaminated with dichromate   This is a fault in technique and 
nothing to do with dichromate being 'attracted to the paper'.
If one understands the fairly simple reactions involved including the effect 
of light on the dichromates and how this affects the   pigmented gum, one is 
unlikely to make this kind of mistake in either understandiong or technique.
Terry
Received on Thu Apr  6 02:01:31 2006
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