Re: wiping KM73 polymer plates
I am feeling like such an alt slut here, talking about solarplate. Like my poor little gum prints are suffering in my darkroom while I am off having an affair in the printmaking lab.
Be a guinea pig and contact that Germany guy Jon mentioned, to find out his neg specs and maybe that will give you some answers. I know that people use imagesetter negs for the process, and so I assume you can use anything, but I'll offer some "intermediate solarplate user" thoughts:
What I have observed all month in the curve calibration process (using PDN) is that if you use a too dense pos, the solarplate cannot handle it. You will get blocked up blacks that open bite. The aquatint screen solves some of that but doesn't solve straight blacks with no detail. Boegh, and most others, solve this problem by using input 100% output 80% and, in essence, clipping 20% of the tonal range of the positive to accomodate the plate. I know when I used to make positives out of lith film for enlarged negs, the Clayton developer sold by Freestyle that was to make lith film continuous tone, if they still do sell it, produced verrrry thin flat negs, so that is a possibility.
It is the oddest stuff, and unlike gum and gelatin in that it apparently hardens from bottom up.
BUT, if you match the plate to the RIGHT colorized positive all of a sudden you get a more straight line curve that is pretty phenomenal, unlike any other process I have calibrated with PDN (cyanotype, van dyke brown, palladium, argyrotype, gum, salted paper) . I was choosing the wrong neg color and increasingly had issues because of other stuff, but my curve looked like a cyanotype curve, and when I finally got to the correct color by trial and error all of a sudden the curve straightened out to look like a carbon or platinum one.
(Speaking of "correct color", that, of course as you know Don since you've used PDN, is different on every printer. I did the mistake of thinking the 2400 color I had chosen would print a good neg on the 4000 printer at school. Nope. One $20 plate wasted.)
This is the biggest benefit to learning a custom curve process is the observation of how substances react to UV light. I have learned so much about solarplate through this sh---y month of trial and error. Believe me, I have been making the plates at home, rushing into the lab to print, it looks horrible, rushing back home, doing another one, etc. etc. until finally I discovered a major error I was doing with curves in this neg/pos bit. Not only do you not use negatives, but you are printing and then judging the ink, not the plate. AND on top of it, you are judging your wiping techique too! So you can imagine room for error and thinking backwards. At one point I was ready to throw in the towel and clip the tonal range. Especially since each plate that didn't work was $8 down the drain.
So I will be an alt slut for a little while longer; there is nothing like a challenge to inspire me. I have seen solarplates printed by others (David Hoptman, APIS for one) that look so gorgeous I know it can be done. Rich velvety blacks and creamy whites. I have gotten creamy whites, good midtones, and everything but the deepest blacks to print beautifully. They were still blocked.
Anyway, that huge preamble of my woes is why I think the German guy is asking for such a specific negative to work from. At least with solarplate you're only wasting about 20 minutes time making a plate. I can't imagine the time involved with making an etched plate and then having it not work out...
----- Original Message ----- From: "Jon Lybrook" <firstname.lastname@example.org>
Sent: Thursday, February 08, 2007 1:55 AM
Subject: Re: wiping KM73 polymer plates