U of S | Mailing List Archive | alt-photo-process-l | RE: digital negative possibilities for gum

RE: digital negative possibilities for gum


I was wondering if you could see the actual dot pattern on the print. You would need a 10x magnifaying glass to check.


From:  "Christina Z. Anderson" <zphoto@montana.net>
Reply-To:  alt-photo-process-l@usask.ca
To:  "Alt, List" <alt-photo-process-L@usask.ca>
Subject:  digital negative possibilities for gum
Date:  Mon, 16 Oct 2006 19:57:51 -0600
>Good evening all,
>Over the last week I have been testing four kinds of gum negs, with
>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
>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
>3.  Cyanogum printed with a negative printed on expensive Pictorico,
>inks, no curves
>4.  Cyanogum printed with a negative printed on expensive Pictorico,
>correctly for cyanotype, magenta and yellow separately, colorized
>These are my observations (NOT declarations or assertions); YRMV:
>1.  Bitmapping surprised me--it actually produced a pretty darn good
>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
>2400, not with Pictorico.  Funny, my cyano layer printed with minute
>spots of lighter tone--not the dreaded speckles--and when I louped
>negative I saw that the printer lays down minute round spots of
>color inks that in turn expose cyano differently, like little mini
>Very interesting. With gum this is no problem--the spottiness, of
>3.  Cyanotype absolutely requires a curve--by the time the
>highlights are
>printed in, the shadows are totally overexposed unless your image is
>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  
>print with no curves, neg just inverted and printed as is, and
>adjust the
>layer with exposure, development, pigment load, brushing. But all of
>already knew that, I'm sure I'll be told. I prefer the all inks
>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
>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
>and scroll down to the very bottom of the images; it'll be there.