Re: Photopolymer problems
As the description of what you are doing unfolds I'm guessing that the "skin" is likely surface exposed material, possibly from being left out in ambient light? Or the material is quite old. There is normally no "skin." Usual shelf life of raw material on this type of plate is about a year under normal storage. It is possible to revive older material with a carbon dioxide bath but not sure this would work with the surface deterioration you have indicated.
--- In PPLetterpress@yahoogroups.com, Neelesh Sonawane <nsonawane@...> wrote:
> I think they are Toyobo Printight Solar Plate KM95 as they are listed in the studio catalogue as Photopolymer for letterpress - KM95. They come in inch sizes (not sure what the full supplied sheet size is) though the studio was kind enough to cut them to A4 for me.
> Processing - (sorry if I'm anally detailed but I'm not sure what might be important)
> warm lamp for 10 mins and set program to 300 with power on NOT full power
> peel protective film off, place in exposure unit
> spread a bit of talc on plate
> align film over, emulsion down
> close vacuum lid and turn on vacuum
> flip top over and run program.
> Remove plate and water wash, brushing in a circular movement. First time I created a plate it took about 10 mins to complete an A5 size. Second time, a bit longer but worked fine. This time (with the problem plates) I was going at it for over 30 mins with no success. I would have tried warm water but didn't have access to any.
> I'm leading to think that the plates are old and the skin is them curing on the surface...
> Neelesh Sonawane
> Graphic design for web and print
> 07949 034 391
> On 10 Apr 2011, at 21:09, bielerpr wrote:
> > Neelesh
> > What brand/kind of photopolymer plates are you using? and how are you going about processing them?
> > Are these direct-to-plate? Those would be the only kind that I can think of off hand that might conceivably have a "skin." If so, this is flashed off in the exposing unit prior to normal processing. ?
> > Gerald
> > http://BielerPress.blogspot.com
> > --- In PPLetterpress@yahoogroups.com, Neelesh Sonawane <nsonawane@> wrote:
> > >
> > > Hello, names Neelesh, I'm new to this list and to letterpress so much appreciative of this lists existence and any nuggets of advice I can glean.
> > > I'm discovering letterpress and photopolymer with a project to print my wedding invites. Time's getting tight due to a lengthy design process (fiancï¿½e = client from hell).
> > > I've run into a problem with the photopolymer plates and wanted to see if anybody had suggestions on how to overcome or the source of the problem.
> > >
> > > I'm printing at London Print Studio and have processed a couple of fairly detailed A5 test plates no problem. Unfortunately when I went to process my first invite plate (one of 3) at A4 size, the photopolymer which has been masked is proving tricky to wash off. I find if I scratch the surface it washes off but only where it's been scratched. Soaking improves the removal but as expected looses finesse in the detail. It appears almost as if the plate has a skin on it which is more apparent with soaking - the surface peels and flakes away but the underneath areas seem to just dissolve.
> > >
> > > I tried 3 plates (pocket money burning this printing), first at 3.40 minutes exposure (which gave the best result strangely). Next at 2.90 and last and worst at 3.00 (the recommended time for the exposure machine). There doesn't seem to be any consistency in the problem areas, the 1st 2 plates were from a newly opened pack and I tried the third from another pack. The film is new and the opacity matches previous successful plate films. In my in-experience I'm stumped. Additionally letterpress is a fairly new string to LPS' bow so the knowledge they have is not extensive, at least the technician who was assisting me.
> > >
> > > Anybody have an idea of what might be wrong or pointers for me to look into?
> > > Much appreciated in advance.
> > >
> > > --
> > > Neelesh Sonawane
> > > Graphic design for web and print
> > > www.sonawane.co.uk
> > > 07949 034 391
> > >
- I have no experience with machine exposure/washout, but I wonder if it is possible that the talc could be causing contact irregularities in the exposure unit? I use talc or corn starch baby powder on plate material before exposure in a vacuum frame (before hand-washout), but I brush the plate off with a very soft brush before putting it in the vacuum frame. It cuts the tackiness of the plate material so the negative does not grab it with any air bubbles that would interfere with proper contact. I'm wondering if too much talc could left on the surface could cause poor contact, and possibly even be the skin you are describing.Sorry if I am way off! I use a different plate material, with different exposure times, etc, so it could be something else entirely!Best wishes,TomIn a message dated 4/10/2011 3:01:34 P.M. Mountain Daylight Time, nsonawane@... writes:
I think they are Toyobo Printight Solar Plate KM95 as they are listed in the studio catalogue as Photopolymer for letterpress - KM95. They come in inch sizes (not sure what the full supplied sheet size is) though the studio was kind enough to cut them to A4 for me.Processing - (sorry if I'm anally detailed but I'm not sure what might be important)warm lamp for 10 mins and set program to 300 with power on NOT full powerpeel protective film off, place in exposure unitspread a bit of talc on platealign film over, emulsion downclose vacuum lid and turn on vacuumflip top over and run program.Remove plate and water wash, brushing in a circular movement. First time I created a plate it took about 10 mins to complete an A5 size. Second time, a bit longer but worked fine. This time (with the problem plates) I was going at it for over 30 mins with no success. I would have tried warm water but didn't have access to any.I'm leading to think that the plates are old and the skin is them curing on the surface...--Neelesh SonawaneGraphic design for web and print07949 034 391On 10 Apr 2011, at 21:09, bielerpr wrote:
- I found out what the problem was. Good that it was fixable but annoyingly it was that printing negative separations direct from Illustrator does not output the blackest black, so the films output were not dense enough.Plates redone, printing all complete. Output not a sharp as I wanted but it was a bit over ambitious to be printing a 3 colour letterpress on a vandercook, with no registration mechanism for my first ever letterpress job.A bit wiser and hooked now.ThanksOn 10 Apr 2011, at 22:51, Prepress wrote:Water temp at Body Temp, use a Thermometer, if you wash out by hand use a eternal 8 (Moebius band) motion.On Apr 10, 2011, at 2:34 PM, Neelesh Sonawane wrote: