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  1. #1
    Colorblind's Avatar
    Colorblind is offline Senior Member
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    Default Minimum line weight in offset printing

    Hi guys, need your opinion on this since I'm not a pressman. I have been shown a design intended to be printed offset on coated paper, most of the design is composed of several diagonal lines of .125 points being at 85c 25y. Is there a minimum line weight for these printing conditions?
    Better train people and risk they leave - than do nothing and risk they stay.

  2. #2
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    First: Great Rael image =)

    Second: Would depend more on your CTP system and press set up than anything. Only once can I recall doing something similar where we had to change the screen angles to account for the direction of 0p0.2 rules set at a black tint (50% if memory serves). But 0p0.125 is a very fine line indeed.

    Even if your CTP system can deal with them well enough (with the right addressability and screen angles), then it's just up to your press handling the tight registration of the tints on those plates. Talk extensively to your press operator and see what they think and see if there are any jobs that they've run that require these kind of tight tolerances on the intended press.

    Outside of a very good CTP and well-maintained press I don't know that this would be feasible. But best of luck!
    "I'm gonna need to see more math I don't understand to believe all this"

  3. #3
    Colorblind's Avatar
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    Quote Originally Posted by maynardsayswhat View Post
    First: Great Rael image =)!
    Thanks, I just love this album :-)

    As for the lineweight, I have the same feeling that 0.125 pts is really thin. Guess I will have to talk to our printer and then have a chat with the designer about real world printing :-)
    Better train people and risk they leave - than do nothing and risk they stay.

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    chevalier is offline Senior Member
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    I was once told the "industry standard" minimum is 0.216pts (I don't remember where or when I was told that). I've held to that number and haven't had any complaints of lines looking too thick by customers when lesser thicknesses have been increased to that amount by prepress workflows. I also haven't had a press operator ever complain there was a line too thin for them to carry.

  5. #5
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    Quote Originally Posted by chevalier View Post
    I also haven't had a press operator ever complain there was a line too thin for them to carry.
    Two issues can crop up besides what has already been mentioned.

    If the press form has very little ink coverage where the fine lines print then they may fail to carry ink and wash out.

    The screening that you use may be too coarse and hence the line may fail to appear on plate or, because it's being halftoned you may see an artifact called "ribboning" in the cyan rule as well as a color shift caused by the yellow screen.

    Go here to see what that looks like: Quality In Print: Halftone screen angles - part 2 of 3
    (scroll to the bottom of the post to see the samples)

    FM screening would solve the halftone problem.

    If you want to see an entire book of insanely thin screened 4/c lines (at least .125 points and thinner - including reverse outs) - you need to see "Spacebloom" Samples from the book can be seen and downloaded here: http://www.spacebloom.net/book/preview/

    but don't really show you just how awesome the presswork is.


    best, gordon p
    Last edited by gordo; 02-08-2011 at 04:05 PM.

  6. #6
    Jackie's Avatar
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    I know this isn't a good reply to the actual question but I'd be tempted to make the lines a spot colour and just go to the expense of another plate and make the job 4 + 1PMS.

    The pressmen would thank you and the final product would probably look better.

    My 2 cents.

    Jackie

  7. #7
    Colorblind's Avatar
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    Just heard from the printer who saw the files and he said he could print it without problem. Thanks guys!
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  8. #8
    claude72 is offline Senior Member
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    Quote Originally Posted by chevalier View Post
    I was once told the "industry standard" minimum is 0.216pts
    It depends of the screen ruling, the shape of the line and the number of inks to be registrated...

    There is no problem to print a solid 0.1 pt line with only one 100% ink...

    ... but a 0.4 pt curved line at 150 lpi will look like a doted-line at some locations, depending of the angle between the line and the screen !

    The best solution for a 0.125 pt line is to print it with a spot color.


    **********


    Quote Originally Posted by Colorblind
    Just heard from the printer who saw the files and he said he could print it without problem.
    Good luck to him !
    Last edited by claude72; 02-09-2011 at 04:27 PM.

  9. #9
    MarkPinSac is offline Junior Member
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    perhaps making those lines a build of 4c would help.....

    I've had this issue pop up several times. The lines would show up on proofs but not on plates. If the piece is 4c and the lines are like say 50% black,
    make them a 4c build of that black value.

    Make sure the pressman registers the job well. Its worth a shot

  10. #10
    John Reveley is offline Junior Member
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    Default Litho line thickness

    I started my career in a litho printer, on the design/repro site, and my experience there taught me that offset litho is a brilliant process. To be honest our presses only went up to SRA2. But a good operator Litho can hold an incredible amount of information. I have two examples of this. Firstly, I created a logo of a lobster in one colour, but the logo was line and tone. It was created at about 8inches high with a 133lpi screen, and was for the front of a menu. Subsequently, the customer wanted some postcards producing, on Astralux board, we decided to use our Little John repro camera to reduce the negative film of the screened logo down to fit the postcard, a reduction to about 10% of the full size! You would need a linen counter to see the screen. This printed perfectly on our press.
    The other example, I created a logo from a product called Letratone, which was made by Letraset, for those of you who have never heard of Letraset, they manufactured letters of the alphabet on sheets on translucent plastic, you would transfer the letters to paper to create sentences and logotypes in the font of your choice, Oh happy days! The tone sheets they produced were different textures that you could rub down onto paper and enhance illustrations etc.
    Anyway my illustration was one of an eagle with it's wings splayed out, its's feathers were created from a tone sheet that had a texture like that of a hair comb, a line vignette, 1 mm to nothing. The illustration was about 12 inches high, but amazingly was photographed (as above) down to 1.25 inches high. It printed really well. I have been a convert to Litho ever since. I cannot envisage a problem printing any fine lines that you could throw out them.
    Good luck.


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