Three-color plate making method gravure

Offset printing adopts UCR (Background Removal) or GCR (Non-Color Structure) yellow, pink, green, and black four-color plate making methods for copying color images. This is characterized by printing materials, inks, and printing methods. It is determined whether the gravure version must also be printed in peace, is it not necessary to adopt the four-color plate-making method?

I. Why Use UCR and GCR

Early offset printing used photographic color separation and did not use UCR and GCR structures. All non-color components in color were reproduced by primary colors. With the development of technology, printing has gradually adopted electronic color separation and desktop publishing systems. Four or more high-speed printing. At this time, there have been three technical problems. First, how to solve the problems of multi-color printing ink layer drying, back supply and gray balance; second, how to save expensive color inks and reduce costs; third is how to improve the printing quality and stability Sex. Provides printing suitable for wet and wet printing. Not only can a small amount of ink be transferred to paper without losing the brightness and thickness of the color, the GCR structure solves these problems very well.

Second, the actual production of the problem

1. The inks used in production are generally somewhat color cast. For example, the yellow color cast is 11%, the black ink is 26%, and the magenta ink is 35%. Each color ink contains more than 15% ash content. Thus, the color gamut that can be reproduced by printing is smaller than the color gamut of daylight. The main difficulty in printing is low-brightness, high-saturation color. In order to reduce the distortion of the reproduced original color, it is only possible to continuously improve the printed material and the process.
2. The characteristics of plain printing, embossing, gravure printing and screen printing are different, so the color space that can be reproduced is also different.
3. There are many kinds of originals for copying, of which the color reversal film has the best quality. In gravure printing, most of the four-color printing uses color reversal film.

Third, the characteristics of gravure printing

Gravure printing with plastic film as printing material has the following characteristics:
1. Gravure printing uses a chrome-plated plate cylinder, which has a very high resistance to printing forces, up to over 1 million impressions. However, gravure cylinders have a long plate making cycle and are costly.
2. The gravure printing uses a recessed cell to carry the transferred ink. The amount of ink transferred is much larger than that of plain printing. Therefore, the gravure prints are very bright in color and can reproduce highly saturated colors and dark colors with a density of up to 2.6. However, the dot enlargement value of gravure printing is larger than that of plain printing, and the regularity of dot expansion is different from that of plain printing.
3. The gravure ink is printed in a dry color, so the printing is wet and dry, and the gravure ink has a much lower viscosity than the offset ink. Therefore, reverse printing will not occur in gravure printing.
4. The color gamut that gravure printing can reproduce is larger than the color gamut of plain printing. Gravure printing can copy high contrast, originals with a density range of 2.6 or more, without having to compress the tone level of the original.

Fourth, the benefits of gravure plates without black version

1. The energy consumption of plastic gravure printing is large. Most gravure printing machines use hot air drying. The energy consumption of each color group is above 20kw. (For example, Toshiba gs120/6 prints at a speed of 100 meters per minute, a single drying oven The power consumption is about 30kw), so one color group can save energy.
2, less one color version can reduce the chance of failure and improve work efficiency.
3, less a color version can shorten the prepress preparation time and improve work efficiency.
4, reduce scrap rate. With one black version, there is no problem of overprinting in the black version. Because the scraper does not scrape off the ink and the knife line appears, the dirtiness of the print can be avoided.

V. Conclusion

In summary, in the gravure platemaking process, a specific manuscript can be analyzed in detail, and on this basis, three-color or four-color plate-making can be selected:

1. For designs with black text (especially small black text), four-color plate making must be adopted.
2. The manuscript without black text can be divided into the following situations.
(1) For prints with color photographs as originals, the three-color plate-making method of y, m, and c may be used instead of the black edition.
(2) For prints with color reversal films as originals, the quality of the originals (mainly the gradation of the original and the keynote of the original) should be determined, if the emphasis of the original is in the dark Dark tone, the screen's color is darker, we must use four-color plate-making method, if the original key tone adjustment in the high light, middle tone and high school tone, dark tone less, and most of the colors in the picture contain a neutral gray component is very Small, bright colors, you can not use the black version of the two-color plate method.