RE: Extending gum range
Can't speak for Judy, but I got 16 steps (with the 31-step tablet -> which translates to log 1.6 ES) with Pthalo Blue several times. Also, once, I was using colorized negatives calibrated for Cyanotype (ES: something like log 1.5) and those were the prints I got the very best results (especially in the shadows -> contrasty & open). Someone with the HP9180 can say the UV density of the negatives according to the following information: Profile: HP Advanced Photo Paper - Glossy, Media: Pictorico OHP - old version, Negative color: R255+B010. Unfortunately I can't -> I don't have a UV densitometer... BTW, I think I'm going to leave the pure gum based calibration approach for "calibrate for Cyanotype, tailor your gum coating solution and exposure time to fit it" approach, which after some testing seems to be the best for my working style & needs... Regards, Loris. 11 Aralık 2008, Perşembe, 11:29 pm tarihinde, Marek Matusz yazmış: > > Judy, > Do I understand you correctly that you can make a gum mix of your choosing > and then expose it to a standard step tablet and get gradation extending > through 15 steps? > Marek> Date: Wed, 10 Dec 2008 22:57:33 -0500> From: jseigel@panix.com> > Subject: RE: Extending gum range> To: alt-photo-process-l@usask.ca> > > > "Gum range" is not a constant... that is, it's tied to a particular > > density of color. A very lightly pigmented emulsion can get 15 or even > > more steps. A very densely pigmented emulsion can get as little as > > four... and long soaks can increase range by opening up the darks.> > J.>
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