Re: solarized gums?
On Feb 14, 2007, at 4:38 AM, ilana swerdlin wrote: Sorry, I didn't notice this part earlier. Maybe I'm not understanding what you're saying here, but an increased concentration of dichromate should require less exposure, not more. And usually, less of the same pigment also requires less exposure than a heavier pigment mix. So I'm not sure what's going on here. But If you want to be able to tell later how to fix a similar problem, it's best to change only one variable at a time. I wish I could see what you've got; it would help a lot. Good luck, Katharine Gum is amazing. Thanks for the help. ilana -----Original Message----- From: Loris Medici [mailto:mail@loris.medici.name] Sent: Tuesday, February 13, 2007 3:22 PM To: alt-photo-process-l@usask.ca Subject: Re: solarized gums? Hi Katharine, This (as Ilana describes) is no doubt the phenomenon you name "tonal inversion". I've read the page that you wrote about this issue again and don't agree with you in: "...The remedy, of course, the way to eliminate the tonal inversion, is simply to reduce the pigment/gum ratio..." Because I've experienced the same effect with a lightly pigmented blue 31-step tablet print before. See: http://www.loris.medici.name/Gum-Test-01.jpg The scan doesn't show it well but, to my bare eyes there's definitely paper white at steps 18, 19 (and maybe 20) + there's definitely tone (where there shouldn't be) at steps 20+. I guess we'll agree that the pigment concentration I used on that print is not excessive since that is easily judged by the scan -> this is Phtalo Blue; as we all know, this is a dark pigment with immense covering power... Regards, Loris. -------- Hi Ilana, My own experience, observations and tests don't support the notion that failure to clear (aka pigment stain) is a function of underexposure, so I wouldn't agree with your tentative conclusion that "parts that should clear are not, because they have not received enough light." If you're interested, some test strips showing the lack of relationship I found between stain and exposure are here: http://www.pacifier.com/~kthayer/html/stainexposure.html It sounds like what is happening to your highlights, if I understand the description accurately, is a phenomenon some people call "tonal inversion." For my take on this phenom, see http://www.pacifier.com/~kthayer/html/tonalinversion.html Hope any of that is useful to you, Katharine
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