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screen printing => Separations => Topic started by: Sbrem on July 31, 2013, 10:40:48 AM
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8 color on black, all films output at 55 LPI, 22.5°, elliptical dots. One of the screens is giving us a horrible moire pattern against the others. Checked and double checked. Can anyone recommend a different angle I could use for just that one color? Printed alone, no moire. All other colors are fine. I would like to try just making the one more screen, before I decide to output the entire job again...
Steve
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8 color on black, all films output at 55 LPI, 22.5°, elliptical dots. One of the screens is giving us a horrible moire pattern against the others. Checked and double checked. Can anyone recommend a different angle I could use for just that one color? Printed alone, no moire. All other colors are fine. I would like to try just making the one more screen, before I decide to output the entire job again...
Steve
went through the same thing yesterday. I kept printing one film at a different LPI. 'almost certain that's your problem, can't think of anything else that would impact only one screen that prints fine otherwise.
pierre
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we output 60 LPI @ 22.5 with wasach
does the film have moire or the screen?
http://printwearmag.com/article/screen-printing/how-to-print-halftones (http://printwearmag.com/article/screen-printing/how-to-print-halftones)
from the article= 14 degrees
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8 color on black, all films output at 55 LPI, 22.5°, elliptical dots. One of the screens is giving us a horrible moire pattern against the others. Checked and double checked. Can anyone recommend a different angle I could use for just that one color? Printed alone, no moire. All other colors are fine. I would like to try just making the one more screen, before I decide to output the entire job again...
Steve
I kept printing one film at a different LPI.
pierre
Did the same thing, rechecked the films with a loupe.
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easy way to check this is to stack the films on top of each other. If the pattern is there, it's in the films!
You should also place the film on the screen and look for the pattern. If it is visible there, the issues is in the mesh to halftone interference. It does not sound like this is the case though . . .
pierre
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I know you guys know way more than me, but I've run into this also using all the same angles, and what I did with the problem film was double the angle on that film and it worked fine. Say your using 22.5 then I would bump to 45.5 or do 56.5 can't say why, but once I match the film up under light they look fine and printed great..
Darryl
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8 color on black, all films output at 55 LPI, 22.5°, elliptical dots. One of the screens is giving us a horrible moire pattern against the others. Checked and double checked. Can anyone recommend a different angle I could use for just that one color? Printed alone, no moire. All other colors are fine. I would like to try just making the one more screen, before I decide to output the entire job again...
Steve
went through the same thing yesterday. I kept printing one film at a different LPI. 'almost certain that's your problem, can't think of anything else that would impact only one screen that prints fine otherwise.
pierre
That was my first thought of course. So out came the loupe to check angles and line count (compared to the other films) Yes, the first one was wrong, so I output again, the one film, and it is correct. It's a really strong one moire too. Looks like re-outputting the whole thing...
Steve
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8 color on black, all films output at 55 LPI, 22.5°, elliptical dots. One of the screens is giving us a horrible moire pattern against the others. Checked and double checked. Can anyone recommend a different angle I could use for just that one color? Printed alone, no moire. All other colors are fine. I would like to try just making the one more screen, before I decide to output the entire job again...
Steve
went through the same thing yesterday. I kept printing one film at a different LPI. 'almost certain that's your problem, can't think of anything else that would impact only one screen that prints fine otherwise.
pierre
That was my first thought of course. So out came the loupe to check angles and line count (compared to the other films) Yes, the first one was wrong, so I output again, the one film, and it is correct. It's a really strong one moire too. Looks like re-outputting the whole thing...
Steve
picture?
pierre
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I was told 61 degrees as a sure fire angle by two isolated sources who were keynote presenters at SGIA about 4-5 years ago in New Orleans.
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I was told 61 degrees as a sure fire LPI by two isolated sources who were keynote presenters at SGIA about 4-5 years ago in New Orleans.
I've used 61 as well. But it's not in the screen, it's on the other inks. It's just one out of 8 films. After enough hours of thinking, it's time to re-output. Onward...
Steve
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OK, all new films, and at 61°. Much better now. Thanks for the help everyone. Sorry the pic is a little fuzzy...
Steve
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Really nice print!
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Looks good Steve glad I taught you all I know LOL, which would have been a one color print with funky halftones :-[
D
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You could do similar work Darryl, even with less colors, don't sell yourself short, man.
Steve
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Steve, do you guys run S mesh? Murakami has a nice "decoder" sheet for this, presuming it was mesh to line angle issue.
http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf (http://murakamiscreen.com/wp-content/uploads/2012/07/HalftoneAnglestopreventmoire.pdf)
I do wish there was a 60lpi on 330/30 guide but this gets ya close.
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Thanks Zoo, an excellent read. I've been a proponent of thin threads for a long time. Years ago my old shop printed a job with bold type and fine lines, white ink on red 50/50
with a single hit. The fabric was a multi-filament, 4XX, which was about as coarse as you could get, but, really thin threads, so a lot of open area. The ability of the mesh to hold fine detail is what got me thinking about it. If I looked at the 86 monofiliment through a loupe, the threads looked like oil pipelines compared to the multi-filament. It took a long time to find a monofilament that would do that. Of course, you do use an awful lot of ink, but it was in the pre-flash days. Now of course, it's PFP for that stuff, but the lesson learned about thread diameter was very educational.
Steve
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Murakamiscreen~
"halftones set to all angles from 1° to 90°."
Now that's a patient group!