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>The contrast range of a given coat of a gum print varies with
>1.) the paper (amount of "tooth" to hold pigment)
>2.) the gum-to-bichromate ratio (what will dissolve, what will harden)
>3.) the bichromate concentration (sensitivity)
>4.) development (length & temp of soak, whether "automatic" or
forced).
>Among other factors.
Another key factor is the gum to pigment ratio! I got tired of soft
looking prints and doubled the amount of pigment I was using. I now
have colors on my newer stuff that are brighter (and consequently in
comparison with one another, have more contrast, than anything I've
seen on tri-color gum before.
I suspect this would have an impact on monocolor gum as well. The
pigment is suspended in the gum, not disolved in it. Look through a
magnifying glass at a gum print and you can see the dots of pigment
clearly. More pigment, and the dots are closer together and hence the
print appears more contrasy. A point would come, however, when more
pigment would become counterproductive since it would serve to "dilute"
the gum.
Gini
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