finer aquatint screen revisited
Hi all you Poly Plate People!
Just finished evaluating some tests I did using a 2540 dpi random dot screen make from a Scitex imagesetter. The results are very good -- better than the 1800 dpi screen made from the Agfa Imagesetter. There is a washout pattern visible in the screen, probably due to exhausted chemistry, but the good new is it doesn't seem to read in the tests. I think the exposure unit burns right through that stuff and so the KM73 plate, for whatever reason, doesn't see it. End result seems to show better tonality than 1800 dpi with no noticeable increase in degradation of the plate. Haven't tested exactly how many prints I can get out of one plate yet however. Under the 1800 dpi screen a client of mine said he was able to get 25 before the plate started showing signs of wear, but I don't know what his workflow is either. There could be other things he could do differently to increase plate longevity.
I'm going to have the vendor send me another test after the imagesetter has gotten a PM and chemistry change to see if the pattern goes away. I'm working on a number of leads on vendors who are willing to do this kind of output on a regular basis for us. Anyone interested in it could certainly find someone with a Scitex imagesetter and get their own screens made - Just tell them you want a positive, 80% density, 2540 dpi, random dot screen. I'll check, but I don't think there are any more parameters than that.
With Susan's recent success with PDN and the KM73 plates, I predict that approach in conjunction with employing a finer random dot screen is going to give an amazing boost to the current standard of tonal quality and smoothness possible with this process.