digital negative possibilities for gum
Good evening all, Over the last week I have been testing four kinds of gum negs, with tricolor gum and gum over cyanotype (cyanogum). My goal was to see if bitmapped negs produced clearer, more brilliant colors as I read somewhere, or even worked with gum, and then to find an acceptable, cheap, low tech beginner mode of gum printing. I made sure to actually attach the negs side by side so all other variables were exactly alike--coating, dry time, development, etc. So here's the skinny: 1. Trigum printed with a negative on cheapy Photo Warehouse OHP transparency with all inks, no curves 2. Trigum printed with a negative on cheapy Photo Warehouse OHP transparency with all inks, no curves, and bitmapped 360 ppi input and output 3. Cyanogum printed with a negative printed on expensive Pictorico, all inks, no curves 4. Cyanogum printed with a negative printed on expensive Pictorico, curved correctly for cyanotype, magenta and yellow separately, colorized neg These are my observations (NOT declarations or assertions); YRMV: 1. Bitmapping surprised me--it actually produced a pretty darn good image! It was softer, a bit less contrasty, but heck, with what little ink bitmapping uses and with the fact you can use cheapy transparency, it is definitely a keeper,especially for teaching beginners low tech gum. 2. "All inks" was a bit smudgy and required drying with the PWOHP/Epson 2400, not with Pictorico. Funny, my cyano layer printed with minute round spots of lighter tone--not the dreaded speckles--and when I louped the negative I saw that the printer lays down minute round spots of different color inks that in turn expose cyano differently, like little mini filters. Very interesting. With gum this is no problem--the spottiness, of course. 3. Cyanotype absolutely requires a curve--by the time the highlights are printed in, the shadows are totally overexposed unless your image is short scale to fit the 4 or 5 stops of that process's range. My next test is to curve just the cyano and use the two bitmap magenta and yellow negs to print gum over. And then next I will probably curve the individual negs and then bitmap. 4. If not printing with a cyano underlayer, you can get an acceptable print with no curves, neg just inverted and printed as is, and adjust the layer with exposure, development, pigment load, brushing. But all of you already knew that, I'm sure I'll be told. I prefer the all inks unbitmapped to the bitmapped--I think. 5. In my eye the better print was produced by a properly curved neg, but how will your viewer know there is a "better" rendition unless all the images are side by side, you know? 6. Bitmapping didn't produce clearer, better colors because of "individual dots laid down side by side and not on top of one another". 7. All methods can be capable of producing fine prints, once the gum printer can meld his/her method to whatever workflow is chosen. 8. Bitmapping has....possibilities...I'm not sure what yet, but it really did surprise me. If you want to see the visual, copy and paste this URL into your browser: http://czaphotography.com/show.php?what=learning&which=1 and scroll down to the very bottom of the images; it'll be there. Bye! Chris CZAphotography.com
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