Expert: LizaL - 4/18/2006

Question
Lisa,
Thank you for answering me back and giving me that article to read.  
To answer your questions.  I am one of the graphic artists and I also run the offset presses
sometimes.  The biggest problem we have is printing on gloss coated paper.  If the dark areas
have to much ink coverage we have set off (offset) problems on the other side of the sheet.  From
what you told me I think we would be alright going to 200% on coated stock because the dot gain
is more forgiving on that paper, is that assumption correct?
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Followup To
Question -
In the custom cmyk color settings, If we were to reduce the Total Ink Limit to 200% rather than
the default 300% how would it effect the colors.  Especially on colors like maroon and dark blues,
colors that would generally uses more than 200% to make them.  The reason we are asking is so
that we use fewer process percentages to reduce offset on the back of the paper.
The other settings are SWOP coated with GCR
Answer -
Hi Phil,

It's hard for me to say because I don't know all the variables of your job. One of the biggest
variables here is, what kind of paper are you printing on? As you know, Total Ink Limit is a
control that's primarily used to handle dot gain. Dot gain will be more prone to occur on thin,
cheaper papers such as newsprint, and not as much of a problem (if at all) on something like a
UV-coated magazine cover, for instance. So paper is going to play a big part in your results here.

You can change the Total Ink Limit to anything you want, but I think your paper is going to
determine a lot about your dot gain and offset on the back of the paper.

Keep in mind too that if you have separations set to GCR, that the black can be controlled that
way. GCR handles the black density by compensating with appropriate amounts of cyan, magenta
and yellow. In the Custom CMYK dialog box, you can also set your black to Light coverage, which
will help reduce dot gain.

You can also use a coarser line screen to control dot gain. Again, this depends on the paper
you're using. If you're printing for the inside of a magazine, that's generally going to be
anywhere from 133 to 150lpi. A newspaper's going to be somewhere around 85 (although it
could be as low as 70), but this will depend on the paper and the presses.

Also -- are you working in a prepress environment and sending this out, or printing this at your
own company? What kind of press is this being printed on? What does the document look like?
I'm guessing that it's text and pictures on both sides of the page. But it's hard for me to tell you
how to set up your custom color settings without seeing what it is you're having printed.

My advice to anyone having anything printed offset is to ask the printer what they want and need
from you, right off the bat. There's honestly no way for me to tell you how the colors are going to
come out, since I can't see your page(s), and don't know what you're printing on.

Probably not the answer you wanted to hear, but like I've always told all my students and will
continue to tell anyone who asks, if you have ANY question about any job that's going to be
printed offset, ask the printer everything about everything you need to know, and go from there.

Also -- I found an article you might want to check out, concerning working with CMYK and
Photoshop:
http://www.dynamicgraphics.com/dgm/Article/28597

Hope this helps!

Lisa  

Answer
Hi again Phil,

From my experience, I'd say your assumption is correct. Glossy paper is definitely more forgiving.

That said, I think you'd have some concerns if you're using supercalendered paper, since it's so thin.

I found this article concerning dot gain and SC paper you might want to look at:
http://www.bmcorp.com/SCCouncil/guidelines.htm

As you can see, they recommend Total Area Coverage to be 260-280. But again, that's using SC paper.

All in all, I think you'd be all right with 200 (if your paper isn't SC). If possible, and especially if this is going to be a big run, I'd definitely do a press check. If worse comes to worst maybe you can adjust on-press if you have to.


I also found this article that might be of some help to you as a guideline, in the future. When you read this, you'll see that this guy is pushing for higher percentages. But he's specifically talking about image reproduction, and not the whole page (or at least that's the way I'm understanding it). I thought the charts at the bottom were helpful.

He also brings up a good point, and that's the part about how you convert your images to CMYK, and how that has so much to do with how they'll reproduce.
http://www.graphicartsmagazine.com/content/view/349/111/


Anyway, it does sound to me like you could do 200% and be all right, especially if you're printing on a gloss-coated paper. The worst you can do is a press check and see what happens.

BTW, let me know, if you think about it -- I'd be interested in finding out your results!

Hope this helps --

Lisa