RE: Extending gum range
On Thu, 11 Dec 2008, Marek Matusz wrote: Judy, Do I understand you correctly that you can make a gum mix of yourWhen you say "of your choosing" you imply that I'd have free range. I wouldn't. With the kind of pigment density we consider necessary for ordinary pictorial gum printing, even with all the tricks discussed here (flashing, et al) I couldn't. I simply make the point that with very little pigment you can get a lot more steps. But I also make the point that you can tailor handling to conditions more than is generally addressed. Test with only dichromate & gum, & no pigment at all... Odds are, with a little trial and error you could get almost the whole range. Add just enough transparent pigment to show some tone, you'll get fewer steps, probably, but still a lot. Etc. The reason I started P-F was to have all my info and "worksheets" where I could find them, but I could't/wouldn't give the space to a full table of contents in each issue, and my "INDEX" got stuck at about issue 4. I know that somewhere I have details on this -- as well as the gum tests I handed the class... For instance, now when I say, "long soaks can open up the darks, hence increase the range," that can be true, or not. In some cases, long soaks will wash away the top, light steps, as fast as, or faster than the bottom steps open up. Whether more top steps wash away, or more bottom steps open up (or maybe they're equal), so that long soaks give maybe more, or maybe fewer, steps are variables controlled by... exposure, emulsion, paper, length of soak, type of size, strength of sensitizer, etc., etc., etc. the details of which I forget now (which is why I put them in print). In sum, you CAN lengthen or shorten scale, often quite usefully, tho never (as far as I know) "freely." As noted, I ran through this exercise in some Post-Factory or other and will look for it. I assigned it to gum classes after they'd gotten the hang of things... It seemed to me to show more about the mechanics, controls, and possibilities than any other "lessons" I could devise. (Besides which, they wouldn't be proving ME "wrong" -- they'd be proving "everything" wrong.) J. -0500> From: jseigel@panix.com> Subject: RE: Extending gum range> To:
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