Re: Gum Chemicals - starting out question

On Thu, 9 Sep 2004, DWAYNE SANDALL wrote:

> Thanks for the feedback, this is exactly the type of information I was
> seeking. One followup question though, is the exposure time going to be
> different for the two types of gum? and other than the issue with mixing
> colours, is there any other issues I should be aware of? I am planning
> on using a metal halide light source.

I found a dramatic difference in speed (exposure time) between two of my
favorite gums... But I note that there are not, IME, "two types of gum,"
but many. In any event this is not something someone can tell you in
advance. Have you got a 21-step? One little test with the 21 step will
give you the range of a gum-pigment combo, and is MUCH more useful than a
test print with a negative, which consists of random densities.

I'll add that I never found the "purest" gum worked the best in
printing. For instance, I found the Daniel Smith "Premier" (or maybe it
was "Premium?) gum almost unusable. That was very light, almost water
white, and about $20 a PINT ! In fact I would have gotten the idea that
the impurities were what made a gum good, except that the totally water
clear Winsor Newton gum arabic worked quite well (as it damn well should
for something like $8 an ounce !).

Judy
Received on Thu Sep 9 21:45:25 2004