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Table of Contents - Procedure last updated 01/25/11 - Procedure first published 02/19/06 |
![]() Suspended Rose - Polymer Photogravure Print by Jon Lybrook 5x7" - 300 ppi image with 1800 dpi stochastic aquatint screen Click image to view unretouched detail at 11X magnification Also see another example... |
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Jon Lybrook's 1800 ppi Aquatint Screen output at 1800 dpi with 35mm film beside it for comparison. Click to Enlarge |
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The Ideal Step Test will have a progressive range of tones, from the blackest black, to the whitest white and as many tones as possible in between, each step as distinctly different as you can make them. This is where experience in the craft of printmaking comes in handy. I like to evaluate a step test by printing it at least three times with Charbonnelle Carbon Black ink, with little or no easywipe. This allows the plate to become seasoned somewhat and gives an opportunity to see what the plate is doing with no fancy additives or ink combinations to throw things off. "Black is truth", as Dan Welden once said.
Once you see how the plate responds to the straight ink, evaluate the tones. If they're too blocked up in the black range, add a little extra easy wipe or 00 burnt plate oil. This should open up the range of black tones. If your whites become too dingy, back off on the plate oil, which can add extra and sometimes unwanted plate tone. Tint base extender may be used to thicken up the ink and bring back more solid whites. You can also try wiping the plate longer (without over-wiping). I sometimes get a nice result from 10% easy wipe, 10% 00 burnt plate oil, and 5% tint base extender added to the Carbon Black ink. Its alot of additives, but sometimes they are called for. It depends on the piece, but in the case of testing, we are trying to bring out the greatest range possible. It helps evaluate our curve and exposure times, as well as the things we may want to do to our ink to bring out the greatest range of tones when we're printing something other than tests. If you've tried all the printerly tricks and it still doesn't look right. Take your best test, and adjust your curve or exposure times as needed, and do another test. There were times when I and the people who know me wondered if I was ever going to be printing anything OTHER than tests. Well, that day eventually comes...until your printer or exposure unit dies, or the manufactuerer changes the formula of your plates or transparency stock...then you have to test again to get back to where you were, alas. But each round makes recallibration all the easier. Thanks to Mark Nelson and Precision Digital Negatives for his 101 Step wedge. Buy his e-book. It's a trove of information and resources. |
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| Ink Color | Toyobo Plate Model | Image PPI | Watts | Screen Exposure | Image Exposure | Washout Time |
|---|---|---|---|---|---|---|
| Black | KM73 | 360 | 5,000 | 10.5 units | 18.1 units | 47 sec * |
| Colored | KM73 | 360 | 5,000 | 10.3 units | 15 units | 60 sec |
| Black | KM83 | 360 | 5,000 | 13.1 units | 22.6 units | 47 sec * |