RE: digital negs for ziatype
POP Pd process is very sensitive to humidity; - humidity barrier - timed drying - pre or post humification - (experimental) adding a humectant to the coating solution such as glycerol Are some tricks you may use (either single or combination) Regards, Loris. -----Original Message----- From: Robert Krawiec [mailto:robk64@yahoo.com] Sent: Tuesday, March 27, 2007 8:12 AM To: alt-photo-process-l@usask.ca Subject: RE: digital negs for ziatype Hi Loris, Thanks for the tips! I'm in Denver, Colorado, so it's pretty dry here! I'm using an Edwards Engineering UV exposure unit. I'll give your tips a try and see what I get... Thanks Rob --- Loris Medici <mail@loris.medici.name> wrote: > Hi Robert, > > What kind of lightsource do you use? Is your working environment too > dry? > > IME, 15 minutes exposure is quite long for Ziatypes > w/ digital > negatives. My standard printing time (for max. > black) w/ a bank of BL > fluorescent tubes is around 6 - 8 minutes (I get > around 27 - 28 steps w/ > the 31 step tablet = log 2.8 DR). Using a more > contrasty mix will help > in getting paper white (try adding 1 drop of 1.25% > Ammonium Dichromate > per 10 drops of coating solution = this should give > you a DR around log > 1.7 - 1.8 = 17 - 18 steps w/ the 31 step tablet), > but you should note > that 2200 OEM inks have plenty density (you can try > to increase ink > amnt. in the printer driver, + %5, %10, %15)... BTW, > Ziatype is faster > and gives better Dmax in high humidity (>= 70%), try > to print as soon as > the paper is surface dry. (= Wait not more than 5 - > 10 minutes after > coating + do not use a hot air stream to dry the > paper!) You may try to > put a piece of impermeable substrate (such as Mylar > or Yupo...) under > the paper to minimize humidity loss during the long > exposure. > > Hope this helps, > Loris. > > -----Original Message----- > From: Robert Krawiec [mailto:robk64@yahoo.com] > Sent: Tuesday, March 27, 2007 7:40 AM > To: alt-photo-process-l@usask.ca > Subject: digital negs for ziatype > > > Hi All, > > I've been trying to create digital negatives for > ziatype on a 2200 with not much success and I was > wondering if anyone out there with expertise could > comment... > > I'm using no contrast adjustment in my mixture, just > FAO and #3 solution, on arches platine paper. > > I'm using black & coloured inks (i.e. not tried PDN > system yet) on pictorico OHP. > > My problem is that I'm exposing for 15 mins with my > UV > lights and still not seeing dmax (close though). My > step table though is not showing paper-white. The > last > few steps are showing clear tones of grey. > > My guess is that I need to mix a more contrasty > mix... > > Any other ideas or suggestions? > > Thanks > > Rob K. > > ________________________________________________________________________ ____________ Looking for earth-friendly autos? Browse Top Cars by "Green Rating" at Yahoo! Autos' Green Center. http://autos.yahoo.com/green_center/
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