Re: muddy gum print--help?
Folks: Thanks for the many helpful replies. I've split my answer in two parts--one about non-VOC size and this one about color balance. This may be more information than many of you want or need. I use stock solutions of pigment. The basic mix is 5 grams in 60 cc of a 50-50 gum/water mix. That is, 30 cc gum, 30 cc water, 5 grams of watercolor paint. When I recently bought Fabriano Artistic paper from Artarama I noticed a watercolor paint labeled Lukas Process Magenta which I ordered and have used in the posted examples. When I mixed this pigment at the above concentration I got a very pale color--cheap paint, less pigment. I settled at 15 grams in 60 cc. I won't use this paint after the tube is empty. It is labeled PR122 but the print is small and I may have written some other number previously. When I was determining printing time and curves, the optimum mix was 3 droppers of my stock pigment, 2 of a 50/50 gum/water mix and 2 of saturated potassium dichromate with an exposure of 2.5 minutes for cyan and 5 for magenta. The yellow drove me mad as I kept needing to increase exposure time--past 10 minutes. Thinking that ammonium dichromate was faster I switched to ammonium for the yellow layer only and got a reasonable looking curve at 5 minutes. The problem with these figures is that they gave me VERY dark and muddy prints. I cut both the times and the concentrations by 10% then about 20% and got the image I posted--then carelessly ruined. My attempt yesterday was to reproduce the ruined print and see if a fourth layer of cyan would help as Sam suggested. Disobeying the fundamental rule of one change per test, I also changed the printing order as suggested by Joe. Parallel with this print--that is, coat both sheets with the same batch of mix, expose sequentially, develop together--I did a print with spray starch. I will write about that in my post on non-VOC size. Both these images are now posted at http://ryberg.zoomshare.com/. The new image is clearly way too magenta. There is pretty clear yellow in the table cloth and the napkins are pretty clear white. I will soon add a layer of cyan and, depending on the results, maybe a layer of yellow. If there is any promise in the print, I'll reprint it with more yellow and less magenta.. I'll worry about changing my triad of color when I get a print that isn't yucky. Thanks for your time and help. Charles Portland Oregon
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