Re: Zimmerman's gum process

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From: Sandy King (sanking@clemson.edu)
Date: 11/11/01-12:55:49 PM Z


>
> > Presumably the air in the jar plays a role, but the 2 processes are
>> different in so many other ways, I could argue that all they have in
>> common is, like compost and chicken soup, a lot of same ingredients, but
>> made and function differently...
>>
>
>Well put. Perhaps someday some curious chemist-turned-alternative-
>process-printer will untangle the similarities and differences, but in
>the meantime I see no reason to assume that everything that's true of
>one dichromated colloid process should be true of others.
>kt

I certainly would not assume that everything that is true of one
dichromated colloid is true of another, and have not come close to
making any such claim.

What I have stated is that there is reason to believe that the
spectral responses of carbon and gum to UV light are very similar.
Judy questioned that but then I tested gum I observed a response to
several different light sources that was virtually identical to what
I saw for carbon. Not identical but similar.

The question of the stability of dichromate in solution, and whether
or not this impacts the printing characteristics of gum, is more
complicated. I can not discount or account for your experiences but I
am strongly suspicious that the differences we have observed between
carbon and gum in this case is not due to a difference of the two
colloids, but to factors related to mixing, storage or contamination
of the dichromate that are not readily apparent.

So that you will not take me for a complete idiot in making
statements about gum printing, in which you and Judy are obviously
experts, I should mention that I have in fact made quite a number of
gum prints, including a few three-color ones. This was quite a number
of years ago but the experience left me not totally ignorant of the
numerous variables that must be accounted for in talking about speed
and contrast of a gum print.

Sandy King

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