Re: son of a gum tonal inversion test

Chris,

You are using the 6 minute exposure time for doing full color prints with 2
gum & 1 Cyanotype layer, correct? Do you use a different exposure time for
the Cyanotype layer?

I would guess that the 6 minute time is not necessarily "arbitrary", but one
that from experience you found gives you a more stable printing with gum.
Since you are doing full color prints with more than one printing, it probably
allows more leeway than if you were trying to do a single coat print. And you
have more leeway in "Hosing Away" the excess density you do not want.
However, a lesser exposure would not give you that luxury, since it would be lost
in the initial soak/development. It's easier to take away than to put it
back.

Also, you are not talking about a huge difference in exposure time under
those circumstances, given multi-coats and the advantages of mechanical
development. I assume that your highlights are clearing as they should, so your
exposure time cannot be that far off, though the calibration step of the
negative's density can compensate for that end of the scale.

I agree, I wouldn't do PT/PD that way, but PT/PD isn't the same type of
animal—I can't hose my PT/PD prints or tease them with a riding crop hehehehhe

Best Wishes,
Mark Nelson
www.PrecisionDigitalNegatives.com

In a message dated 12/6/05 10:48:28 PM, zphoto@montana.net writes:

> 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.
>
Received on Wed Dec 7 03:41:39 2005