How to Use Spot Color in Designing a Plate (top)

Nowadays, more and more commercial prints, packaging and decoration prints, especially high-end albums, book covers, and packaging products, are pursuing the use of special colors to achieve extraordinary results, such as a large area of ​​special color printing. Background color or fine lines, patterns, etc. Therefore, spot colors are used more and more frequently in plate printing. Correctly using spot colors in plate printing is very important for achieving customer requirements and the quality of printed products. According to many years of work experience, the author talks about the pre-press treatment of spot colors.

The role and characteristics of spot colors

Spot color printing refers to the use of specific color inks, such as fluorescent colors, metallic colors, and bright orange and green colors, to replace or print inks of three primary colors, and special color separations are required for each spot color plate. Or channel, making special plate-making film. Spot color printing has the following features.

1. High color reproduction accuracy

Each spot color has its own fixed hue, which can guarantee the accuracy of printing color reproduction, and solves the problem of inaccurate color reproduction caused by poor stacking of ink in offset printing. In addition, the same spot color can maintain a consistent hue no matter where it is printed, thus avoiding the color deviation caused by the printing environment, equipment, and process.

2. Good quality in the field

Spot colors generally use solid colors to define colors, and they can also be used for screens to render any shades of special color tones. For example, gold/silver screens can be superimposed on four-color images to obtain a special effect. In addition, the large-area spot color printing can achieve the flat color uniform and evenness, and eliminate the polychrome overprint rose spots.

3. Wide color gamut of spot colors

From the Phtoshop's coloring menu, you can see that any spot color selected is a four-color hard-to-copy color, and its color gamut is wider than the CM丫K color gamut. Therefore, some special requirements for printing colors must be specified. Color to achieve, and have a certain anti-counterfeiting effect.

4. save costs

The number of imprints is determined by the number of imprints. Generally, 1,000 imprints are printed by imprinters, and four-color imprints are printed by four imprinters. If the designer can design some color patches to be printed in a spot color, the printing cost can be reduced.

Spot color design considerations

Some customers require the output center to take a four-color document to issue a spot color version for spot color printing, making the output center very difficult; also some designers want to use multi-color printing, but do not know how to do standard distribution files. I hope that the following will give you some help in devising the spot color design.

When determining whether a product is spot color printing or four-color plus spot color printing, designers should pay attention to the following issues.

(1) When designing spot colors, we must use the spot color ink option. The inks specified by the software are divided into two major categories, spot color ink (Spot CoI0r lnk) and four-color ink (Process Color. Ink). When designing spot colors, Spot CoIor Ink must be selected. Designing a spot color has a color version that cannot be set as freely as four-color printing.

(2) Consider trapping traps when designing spot colors. In order not to overprint the spot color and the image, the area corresponding to the image on the spot color shall be hollowed out. In addition, for accurate overprinting, the area of ​​the hollow part of the spot color should be slightly smaller than the image area (trace), otherwise there will be a clear leak at the edge of the spot color area. Since spot color printing is mostly printed in the field, it is necessary to make spotted spot colors when printing with images, and a certain amount of trapping is required to achieve accurate printing results. If spot colors (opaque spot colors) are required to completely cover other colors, you don't need to do hollows or traps. However, you must select the overprint option so that spot color inks are superimposed on the bottom picture.

There are four principles to follow when making traps: all colors are expanded in black or gold/silver, because black covers other colors; bright colors expand in dark colors; yellow expands in cyan, magenta, and black; Pure magenta expands below each other in equal amounts.

(3) When making a spot color version with a tone change, consider the screen angle when the dots are overprinted, otherwise a moire will occur. Spot color version and other color version of the cable angle to be a difference of 30 ° If there are three spot color version, the three spot color version of the cable angle is best designed for 15 °, 45 °, 75 °, and do not put the dark color The spot color network line is set to 90. In order to avoid moire. When four-color plus spot color printing, it is best to make spot color version of the cable angle and other four-color version of the difference of 15 °, but the lighter spot color can not consider the issue of network cable angle.

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