Prepressforums.com

BobVob · #1 (**permalink**) 05-09-2005, 03:33 PM

Hi,

Are there any other shops on the planet besides us that are running CMYK jobs with a polyester CTP setup?

What type of RIP/platesetter/press are you using? We have Xitron Navigator RIP, Agfa Avantra 25 imagesetter and a 2-color Heidelberg SM52 press (making things more complicated having to do two passes to get 4 colors on the paper). Does anybody have any tips or experience with this type of workflow, or any recommendations - other than dropping $1,000,000 on a proper 4-color press, which unfortunately isn't really an option right now?

#2 (**permalink**) 05-10-2005, 07:23 AM

I bet registration is a bitch running 4c on those poly plates, with the stretch you get from them.

Cory · #3 (**permalink**) 05-10-2005, 07:32 AM

I don't recall who, but I do remember our rep telling us that 12 mil poly plates are out in the market...

that would help with the stretch issues i'm sure.

BobVob · #4 (**permalink**) 05-10-2005, 09:04 AM

We had a lot of problems with the registration in the beginning, but with careful punching and a few extra guidelines imaged on the plate, the pressman has been able to produce a pretty consistent and tight job - our main concern now is maintaining color accuracy across the job. There always seems to be problems with certain screen densities filling in, or just shifts in tone from start to end of the run. The major setback we are finding, is that by the time the magenta and black are on the heads, it's of course too late to make any density adjustments to the first two colors. I guess what I'm asking is if anyone has had success running 4c jobs like this, or if it is always going to be a losing battle given our two-color press? Does anyone run 4c with METAL plates on a 2-color press? How do you (or the press operator) determine what densities to run each ink at if you can't see the final result until the 2nd pass?

#5 (**permalink**) 05-10-2005, 09:25 AM

We run some 4c on some of our 2c presses. Our 4c press was profiled and the proofs are set to match the press profile. Each seperation - CMYK has a density we run to in order to achieve the right color. We first output proofs of just the blue & blk seps together, and then the red & yellow seps together. Now the press operator can run up to density (for each color) and check the press sheet against the proof of the same two colors. This works great every time, if we don't tell anyone it was run on a 2c they would never know!
Good luck.
by the way - this is on metal plates

Vee

pressman2 · #6 (**permalink**) 05-10-2005, 09:27 AM

If your press operators use a densitometer during their first pass, and can hold the range specified by the ink manufacturer, they should be fine with the colors on the second pass. That's about the best you can do, unless you are blessed with a super pressman that has that God given ability to visualize 2 colors at a time on a 4/c job. I would really think that the second pass would have more issues with the registration than the color.

prepress_brillance_43 · #7 (**permalink**) 05-10-2005, 09:36 AM

I'm personally impressed that you guys are printing this way. I would like to see some finished work and see how tight the registration is. We had a two color Kamori in the lab while I was in school and the lab teacher was the pressman, he would print a bunch of collateral for the school, his 4c NEVER hit registration and I can remember times that some of the students who were more interested in the press(I was always on the comps) would always bitch about how bad his printing sucked. I guess when you are a university and you take donations of equipment instead of out of budget for new, it leaves you using outdated stuff, hence making the print suck and/or tough to print. ...maybe was the teacher/user?... i guess if it works for you then it works for the customer...

seetomtype · #8 (**permalink**) 05-10-2005, 10:15 AM

We print 4cp on 2color Towers using 8 mil plates, too. We are twice blessed
though. Our lead operator is very skilled at seeing a 2+2 build, and we
have 2 towers that have almost exactly matching cylanders (sp). We
can set them both up, go 2 + 2 and have a good idea about color in about
10-20 minutes. I have never heard of anyone else doing it this way though.
You make do with what you have when the company won't fork over cash
for equipment :wink:

pspdfppd · #9 (**permalink**) 05-16-2005, 11:27 AM

funny I just read this post...

Our 2 color heidelberg pressman is running 21 different 4 color 5 inch square 6 panel brochures just today. (4 up, 29.375x 5 inches) We made color keys for the cyan and black plus magenta and yellow and I just saw that he's matched it very well. They are high quality travel brochures.

Plus....we use polyester plates all the time for 4 color work, as long as the runs aren't over about 10,000. We have one guy who can match our digital proof right on the money (AGFA Sherpa's) though other pressmen have not been as good. I guess it takes some talent and perserverance to get it right.

We are using AGFA's setprint 8 mil plates and have been for 5 years.

Sparky · #10 (**permalink**) 05-16-2005, 05:57 PM

We have 3-2/color Ryobis that I make 4/color process plates for a lot more recently. Our Platesetter is a Printware PlateStream running 12" x 8 mil. polyester material. I have worked with 40" 6-unit Kamoris and I am here to tell you the plates the PLateStream produce (mind you 150 lpi max at 2400 dpi) will compare to fit with most of those Kamori jobs. It's a matter of mounting them like they were made from glass and not cranking the clamps like you would a metal plate. Our run lengths though can only go as high 40-60K then you begin to see a bit of breakdown, but most of our jobs rarely exceed this number.