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: alt-photo-process-l@usask.ca 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
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