Re: son of a gum tonal inversion test

  I reduced exposure from 600
> to 75 exposure units based on the previous test to give me maximum
> density at step #1 today. I based today's corrected exposure on last
> week's intentionally overexposed print which first exhibited the tonal
> reversal. (There's a little variation there probably due to mixing the
> emulsion slightly different today, but the maximum printed density is
> close to before.) I ran two tests with the same emulsion batch & paper
> the difference being I intentionally coated both at the same time,
> printed and processed one sheet immediately, and let the other sit in
> the dark for an hour before exposing it. The latter print is just
> barely darker and this difference could probably be equalized by letting
> the print soak a bit longer. (Both were autodeveloped for 1 hour in 3
> changes of water.)

Fascinating stuff Joe.
I have no clue for the weird beard (LOL) stuff but application, not theory
here. This is why I chose to stick with a 6 minute exposure time, instead
of the exposure time that actually had step 1 be the maximum black (a time
for gum that was for me around 4 minutes or so). Even though the six minute
time produces some merged steps on the Stouffer's, once my curve was
calibrated for that time, I got a stable coat and a nice and colorful coat
because the gum hardened layer was deeper and therefore more pigment
remained on the surface of the paper (and not sunk into the paper! Tho i
don't get that problem anymore with glut). And my shadows didn't block up
because the curve takes care of that. Gum is the only process that I chose
to calibrate in this manner--arbitrarily choosing a time of exposure instead
of a standard printing time. I would never do this with palladium, for
instance, but for gum it works because it is a layer of hardened stuff with
depth--different than other processes.

Why on EARTH your numbers that should be black are white...I'm gonna guess
that you had enough exposure to keep the pigment from sinking into the paper
but not enough to have any of the stuff stay on during development.
chris
Received on Tue Dec 6 21:45:22 2005