U of S | Mailing List Archive | alt-photo-process-l | Re: gum negatives redux

Re: gum negatives redux

Using half the dichromate would increase contrast, correct?
And you use 1.5-2x the highlight exposure?
----- Original Message -----
From: "Loris Medici" <mail@loris.medici.name>
Sent: Sunday, September 13, 2009 10:24 PM
Subject: RE: gum negatives redux

> I'm not them (Jim and Katharine) but my 2c would be:
> Was your coating solution for shadows very dark / heavily pigmented? If yes
> it could be that you need a longer exposure indeed; since as I know it
> pigment amnt. will affect exposure time and contrast of the emulsion, so,
> what you're experience here is in line with gum principles and expected. But
> if only you've a rather extreme coating solution there...
> BTW, FWIW, I usually use half the dichromate and 1.5-2x the exposure when
> exposing for shadows. Works better for me...
> Regards,
> Loris.
> ________________________________
> From: Jim Larimer [mailto:jrlarimer@gmail.com]
> Sent: Monday, September 14, 2009 7:20 AM
> To:
> Subject: Re: gum negatives redux
> Paul, my scientific answer is: Hmmmm? That usually works just fine, but
> then, last night I tried the same approach with the same results that you
> experienced! It may be that there is surfacing another variable in gum
> printing, bringing the number to 1243. Sorry, I have no answer, just egg on
> my face ;(
> Jim
> On Sun, Sep 13, 2009 at 5:24 PM, Paul Viapiano <
viapiano@pacbell.net> wrote:
> Katharine & Jim...
> I tried the ivory black at 1 gram / 2 ml gum in a 1:1 ratio with the
> pot dichromate.
> Exposed for approx half my highlight exposure, but at 25 min in
> development, there was hardly any black pigment left on the print.
> I need to step-tablet this negative and try a few different
> pigments...but...
> When doing an exposure for the shadows, would you expect a much
> shorter dev time?
> Paul