Re: Gum hardening: top down experiment

On Apr 11, 2006, at 11:18 PM, Dave Soemarko wrote:
>
> The set exposure time for our test would be the minimum time
> required to
> make reasonable gradation when exposure is made from the back. For
> example,
> one could expose so that 4 steps are obtained. Then use the same
> exposure
> time for exposing from the front with the step tablet covered with
> a piece
> of mylar. The idea is that we shouldn't underexpose such that both
> cases
> will not work or overexposed so that both will work.

This seemed simple enough, so I used the same gum/pigment mix I used
the other day (ivory black mix plus a drop of Prussian) and used
step tablets as you suggested, covering the front-exposed tablet with
mylar to control for the effect of exposing through mylar, and
exposing them both for the time that the back-exposed print was
exposed the other day, while I busied myself cleaning out the
chemicals cabinet in the studio.

  But this time I apparently brushed the coating slightly thinner,
because the color is paler and both prints were overexposed. They've
been developing for more than an hour and they look pretty much the
same so far: both have released the unhardened gum from steps 21 down
to 11 and steps 1-10 are all the same tone, on both. So I fear I've
gotten into your last category, of overexposing to the point that
both work. I'll leave the strips to develop longer, while I go do
some other things, but it's clear that this isn't going to make the
clean distinction (one works and the other doesn't) you were hoping for.
Katharine
Received on Wed Apr 12 13:54:44 2006