Adobe InDesign CC 2015 - Manual (Page 616)

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Printing
Last updated 6/6/2015
Your design workflow may require a certain color to be set to overprint. For example, you want to print all the text in
your publication in a specific color. Consider the following options:
• Create an object style that uses the spot ink as the fill or stroke with a matching overprint fill or stroke.
• Create a separate layer for objects that contain your spot color and assign them to black.
• Create a composite PDF and change overprint settings within the PDF.
• Assign overprint settings in your RIP.
• Apply overprint settings to an image or object and add it to your library, or edit a placed file in its original
application.
Determining when to overprint manually
Automatic trapping in InDesign—either as built-in trapping or Adobe In-RIP Trapping—nearly eliminates the need
for manual overprinting. However, manual overprinting can be an effective solution in the rare cases when you can’t
use automatic trapping.
Use the following guidelines to determine whether or not to use overprinting:
• Consult with your service provider to see if their output devices support manual overprinting.
• Overprint when the artwork doesn’t share common ink colors and you want to create a trap or overlaid ink effects.
When overprinting process color mixes or custom colors that don’t share common ink colors, the overprint color is
added to the background color. For example, if you print a fill of 100% magenta over a fill of 100% cyan, the
overlapping fills appear violet, not magenta.
• Don’t overprint when using a stroke to trap two process colors. Instead, you specify a CMYK stroke color that uses
the higher value from the corresponding inks in each original color.
• Make sure that you and your prepress service provider agree on when and how to overprint manually, because doing
so will significantly affect trapping options specified in the Print dialog box. Overprinting is supported by most, but
not all, PostScript Level 2 and PostScript 3 devices.
Overprinting page items
You can overprint strokes or fills, paragraph rules, and rules above footnotes. You can also simulate overprinting of spot
colors.
Overprint a stroke or fill
You can overprint strokes or fills of any selected paths using the Attributes panel. An overprinted stroke or fill doesn’t
need to be trapped, because overprinting covers any potential gaps between adjacent colors. You can also overprint a
stroke to simulate a trap (by overprinting a color you’ve manually calculated as the proper combination of two adjacent
colors).
Keep the following guidelines in mind as you apply manual overprinting:
• If you use the Overprint Fill option on a 100% black stroke or fill, the black ink may not be opaque enough to prevent
the underlying ink colors from showing through. To eliminate the show-through problem, use a four-color (rich)
black instead of a 100% black. Consult with your service provider about the exact percentages of color to add to the
black.
• When using a stroke to trap objects (but not text characters), adjust the stroke alignment so the stroke falls outside
the path or object, rather than inside or centered on the path.