Re: Gum hardening: top down experiment

On Apr 12, 2006, at 12:54 PM, Katharine Thayer wrote:

>
> 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.

I finally took these test strips out of the water, after 3.5 hours
development. They were both exactly the same: some blocked steps,
then four steps of decreasing tone, then blank (except for the
numbers of course) from step 11 through step 21.

Katharine
Received on Wed Apr 12 16:22:42 2006