Re: muddy gum print--help?
Charles, how's it going, any progress? I wouldn't be surprised or offended if you were feeling at this point that you can't deal with any more conflicting input; so feel free to ignore my thoughts, but here they are, for whatever they may be worth to you. in no particular order:
(1) is this the print you asked for help with before, where you said that you weren't getting green where you should be getting green in the tablecloths, after printing the first two layers (blue and yellow)? Did you solve that problem, or do you know whether that might still be the case, that your blue and yellow aren't adding to green without the magenta? (if you changed the order of printing without solving the problem, then it's probably still there). The reason I'm asking is that if your blue and yellow together aren't adding to green, that's one problem, but if you are getting green and then the magenta is neutralizing the green to grey, that's a different problem.
(2) I don't recognize the color index number of the Lucas process magenta; are you sure that's the right number? Also, if you're using Daniel Smith Hansa Yellow Medium, that's PY97, not PY3. PY97 is a strong, clear yellow that should print these greens well. Another thing I don't understand is your statement that you had to go to ammonium dichromate for the yellow because with potassium dichromate the yellow takes an inordinately long time to print. That just doesn't square with my experience.
(3) as Marek predicted, I have to comment that I don't find ultramarine any wimpier than indanthrone; they are both in the middle ground as far as pigment strength. Thalo of course is the strongest, then prussian, which is my current favorite blue for tricolor, then ultramarine and indanthrone, about the same, and then cerulean and cobalt are much weaker pigments, although I doubt most people would consider the last two for tricolor.
However, I do wonder if the ultramarine is the best choice to balance your other two pigments. I've never used ultramarine with PY 97, and it's not clear to me from the reflectance curves how well they would mix, and as I said I don't know your magenta so I can't make any guess about how those two would blend, but something's definitely wrong with how your colors are mixing.
(4) if you have reprinted with much more pigment and got better results, then I'll eat crow, but I have trouble believing that you're printing with as little pigment as you'd have to be using to cause this result by underpigmenting alone. I did quite a study of printing with very little pigment from 2001-2004, and I'd say from my experience that you'd have to be printing with just barely tinted gum. If that's so, then I'll agree, you need more pigment, but since I do know from other things I've seen that in the past you've printed with more normally printed mixes, I'm inclined to discount this explanation.
For example, my print linked just below was printed with so little yellow in the mix that when the yellow layer was printed, it didn't even look yellow; it looked like titanium buff, sort of a dull pale beige. Only when the other colors were added, did the yellow pull itself together and look yellow. I adjusted the other colors downward to keep the color balanced, but you can see that even with very little pigment, this print doesn't look like yours. So I really don't think it's about the pigment, but I could be wrong.
(5) I agree with Jim that I don't think it's the size that's your main problem. A magenta stain should be magenta (red-violet); this looks more like pale burnt umber or something, so if you're getting a stain, it's not just the magenta, it's a combination of colors that's adding to this pale overall brownish pink fog. But, that's not what's causing the problem with your colors IMO.
(6) It reminds me a bit of how Fabriano Uno used to print for me unsized: it would just swallow up the color, attenuate the DMax like crazy. Fabriano Artistico Extra-White isn't the same paper, although when Fabriano first brought it out, they made a big deal of it being the same paper with a different name, but I wonder if it shares that quality with its predecessor. I would try sizing with one of the nontoxic alternatives that have been suggested.
(7) which brings us finally to negatives/curves. You said you'd show the curves if we thought it was necessary; I think I'd like to see the curves, if you haven't solved the problem yet. There's something weird going on here. The only explanation I can think of for why you'd need such a longer exposure for the yellow than for the other colors is if there's something about that negative/curve that's holding back the exposure needlessly (or, if it's something about your light, which I think is less likely, but possible). I agree with other commenters that your values/tonal relationships look good, though overall too light, but there's something that's screwing up the colors, either an incompatibility of the pigments themselves, an imbalance in the pigment concentrations, or the curves are interacting with each other in weird ways.
Them's my thoughts so far,
On Apr 12, 2009, at 9:35 PM, Jim Larimer wrote:
Charles, it seems that all gum printers have their own systems...but, it takes a bit of time and experimentation to work that system out. First of all, I second Paul's advice about Gamblin PVA, I use it exclusively, and am happy with the results that I get. In the print that you have identified as being "muddy," it does not appear to me to be a problem with sizing. Another layer of yellow and one of red would, I think, solve the problem. Maybe you would need a a bit of blue as a final layer for more "oomph" but I don't think so. I think that what I am suggesting is pretty much what Keith has already said.