Multicolor Printing
Multicolor printing is printing in more than one color: two, three, four, etc.
The addition of a second color provides a variety of design possibilities: not only can the two colors be used separately, but they can also be combined as solids and screened tints to produce a wide range of colors.
Although it is possible to use any two colors, one of the most common combinations is black and a second color. This allows halftones and text type to be printed in black, while the second color can be used in a more decorative manner.
The addition of a third or fourth color extends the color possibilities. While technically everything that has been said about one-color and two-color printing applies to three-color and four-color printing, there area few factors to keep in mind when designing three-color and four-color jobs.
In many cases the designer may find that a three-color job costs as much as a four-color job. The reason for this is that most printers use either one-color, twocolor, or four-color presses. To do a three-color job the printer has to either make multiple passes on his one-color or two-color press or use a four-color press for only three colors. Ideally, one pass through the press is preferable; it is less expensive and it offers the printer an opportunity to correct or balance the color while the job is running.
Although it is possible to print an unlimited number of colors, four is generally the maximum. One reason for this is that a four-color press is an industry standard. Also, from the designer's point of view, four colors plus tints and combinations will give him as much color as he needs for all but the most unusual jobs.
Flat-tint Halftone. The flat-tint halftone provides an inexpensive way of introducing color into a halftone. The black and white halftone is printed (surprinted) over a flat background tint of a second color. The designer should keep in mind that the darker the tint the darker the highlights will be, hence the flatter the halftone will appear.
Duotone. A duotone is a two-color halftone made from a regular black and white photograph. To make a duotone, the photograph is shot twice (at different screen angles), once for the black plate and once for the color plate. The black plate is shot for contrast to hold the dark, or shadow tones; the color plate is shot for the middle tones. When printed, the halftone dots from these two plates produce a complete range of tones.
For the best duotone results, use a photograph that has a full range of tones from black to white. And remember that the second color should not be so strong or dark that it will overpower the black; the best second color for duotones is gray or pastel in tone.
It is also possible to print a duotone using black for both the first and the second color. This is called a double-black duotone. Double-black printing represents an effort to overcome the limitations of the printing process. Using a single plate, it is impossible for a printing ink to match the rich, solid blacks of a glossy photograph. To compensate, the printer adds a second black plate for the shadow areas. When printed, these two plates combine to produce a rich, dense, black and white image with excellent contrast.
If you work with duotones, it is wise to ask the printer for a sample of his duotone printing; there are a number of ways to achieve a duotone effect and you may not always get the result you anticipate.