Printing: Spot Color versus Process Color
If your document will be commercially printed, there are several factors that determine where to use process colors or spot colors in the document.
The printing process that will be used
Some processes, such as digital printing, cannot handle spot colors. Some presses can handle a maximum of four ink colors (spot or process). Using a fifth, spot color to extend the color range may be either impossible or cost considerably more. Check with your print shop on any possible limitations.
The number of colors in the job
The number of colors you plan to use will be the main factor in deciding whether to use process color or spot colors.
Does your project make use of only one, two or three colors (including black)? Then you'll want to use spot colors. Spot color uses a different ink for each color. Note that objects with transparency applied always separate to CMYK (this means you cannot use transparency for this type of job). If your budget is limited:
Obtain a two-color look by printing on colored stock and using only one spot color.
Use tints (percentages) of spot colors to create shadows or highlights, thus giving the impression of a broader color range.
Does your project call for full color (e.g., does it contain scans of color photographs)? If so, you will need to use process colors, which simulate virtually any color using only the four ink colors, cyan, magenta, yellow, and black (known as CMYK).
Does your project call for both spot and process colors? For example, a marketing brochure may require the use of a spot color to faithfully render the corporate color and the use of process color to reproduce scans of photographs. Remember, though, that the greater the number of colors used, the more film, plates and ink will be required, which adds to the cost of the job.