Using Help | Contents | Index Back 155
Adobe Illustrator Help Applying Color
Using Help | Contents | Index Back 155
Spot colors
A spot color is a special premixed ink that is used instead of, or in addition to, CMYK
process inks, and that requires its own printing plate on a printing press. Use spot color
when few colors are specified and color accuracy is critical. Spot color inks can accurately
reproduce colors that are outside the gamut of process colors. However, the exact
appearance of the printed spot color is determined by combination of the ink as mixed by
the commercial printer and the paper it’s printed on, so it isn’t affected by color values you
specify or by color management. When you specify spot color values, you’re describing the
simulated appearance of the color for your monitor and composite printer only (subject to
the gamut limitations of those devices).
For best results in printed documents, specify a spot color from a color-matching system
supported by your commercial printer. Several color-matching system libraries are
included with Illustrator; see “
Loading colors from other color systems” on page 166.
Minimize the number of spot colors you use. Each spot color you create will generate an
additional spot color printing plate for a printing press, increasing your printing costs.
If you think you might require more than four colors, consider printing your document
using process colors.
Process colors
A process color is printed using a combination of four standard process inks: cyan,
magenta, yellow, and black (CMYK). Use process colors when a job requires so many
colors that using individual spot inks would be expensive or impractical, such as when
printing color photographs. Keep the following guidelines in mind when specifying a
process color:
• For best results in a printed document, specify process colors using CMYK values
printed in process-color reference charts, such as those available from a commercial
printer.
• The final color values of a process color are its values in CMYK, so if you specify a process
color using RGB, those color values will be converted to CMYK when you print color
separations. These conversions will work differently if you turn on color management;
they’ll be affected by the profiles you’ve specified.
• Don’t specify a process color based on how it looks on your monitor unless you have set
up a color management system properly and you understand its limitations for
previewing color.
• Avoid using process colors in documents intended for online viewing only, because
CMYK has a smaller color gamut than a typical monitor.
Using spot and process colors together
Sometimes it’s practical to print process and spot inks on the same job. For example, you
might use one spot ink to print the exact color of a company logo on the same pages of an
annual report where photographs are reproduced using process color. You can also use a
spot color printing plate to apply a varnish over areas of a process color job. In both cases,
your print job would use a total of five inks—four process inks and one spot ink or varnish.
Important: If an object contains spot colors and overlaps another object containing
transparency features, undesirable results may occur when exporting to EPS format, when
converting spot colors to process colors using the Print dialog box, or when creating color
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