RE: dark gums
Hi Ilana, What substrate you use for your digital negatives - is it plain paper or transparency film? And, what kind of lightsource do you have? Diluting your ammonium dichromate solution will increase the paper's contrast and decrease printing speed. FWIW, I print using "plain paper" digital negatives (black ink only) and 25% ammonium dichromate. My printing times are 4 to 6 minutes (cyan: 4 minutes, yellow: 6 minutes). My lightsource consists of 8x40W BL tubes at 3" from glass. I use pigment stock solutions; I pour all of the 15ml tube into film canisters, top it with gum solution. My gum solution is made by mixing 1 parts gum powder with 2 parts water (I use sodium benzoate to preserve it). I put very little pigment/gum stock solution in my coating solution (two thin - thinner than my little finger - spatulas per 5ml coating solution) and I coat very thin (haven't measured precisely but I use circa 2.5ml combined gum/pigment+dichromate solution per A4 / Letter size prints with at least 1" border - my coating tool is a foam brush). Regards, Loris. -----Original Message----- From: ilana [mailto:ilanamahala@adelphia.net] Sent: Wednesday, January 24, 2007 4:06 AM To: alt-photo-process-l@usask.ca Subject: RE: dark gums ... 2. Extremely long exposures that still provide little image, with pigment not coming out [too long of exposures? not enough contrast in negative? Too much pigment?] ... Also, I have a 30% saturated ammonium dichromate solution...would it be too much a variable to change this to compensate with/for exposure? Could I add more distilled water to this already mixed solution? ...
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