Color Sequence and Overprint Efficiency of Newspaper Printing

       Order is particularly important. The determination of printing color sequence and overprint efficiency of newspapers is discussed from the following aspects.Color Sequence and Overprint Efficiency of Newspaper Printing

1. Wet press wet printing method

Newspaper printing belongs to high-speed printing; In terms of ink overprint time, it belongs to wet pressing mode; Due to the rapid absorption of newsprint, from the perspective of ink drying, the first and second colors belong to wet press drying, while the third and fourth color overprint belongs to wet press drying.Color Sequence and Overprint Efficiency of Newspaper Printing

2. Brightness of ink

Put the high brightness ink at the end, and the picture will be more gorgeous.Color Sequence and Overprint Efficiency of Newspaper Printing

3. Adhesion of ink

        Generally, the ink with large adhesion is printed first. In addition to the biggest tack value of black first printing, there are also reasons that the color of post printing is easy to register for black.Color Sequence and Overprint Efficiency of Newspaper Printing

       The tack value will change in different printing States, and it is usually difficult to accurately control the tack value of printing ink. When the binder of the ink is absorbed by the paper, the tack value of the ink will increase, which occurs in a short time between the first color and the second color. Color Sequence and Overprint Efficiency of Newspaper Printing

      The increased tack value during this time may have properly transferred the ink amount of the second color (the lower tack value) to the first color ink film. Color Sequence and Overprint Efficiency of Newspaper Printing

      Therefore, each color ink can have the same tack value.Color Sequence and Overprint Efficiency of Newspaper Printing

       Yellow ink in addition to the minimum tack value must be post printed, the lack of visual concentration is also a reason for post printing. Because of its thick ink film, if yellow is printed first, there will be an efficiency problem of transferring a thin ink film to a thick ink film.Color Sequence and Overprint Efficiency of Newspaper Printing

        In this way, the tack value will be reduced and the viscosity grade between the first color and the second color will be destroyed.Color Sequence and Overprint Efficiency of Newspaper Printing

4. Absorption of newsprint

Due to the high absorption of newsprint, in order to prevent through printing, it is not suitable to use the color sequence of printing black ink first.Color Sequence and Overprint Efficiency of Newspaper Printing

      During printing, the ink film of the former color must reach fixed viscosity before the latter color is successfully transferred to the former color.Color Sequence and Overprint Efficiency of Newspaper Printing

       The fixing time must be shortened by the use of fast drying ink and adjusting tack value and density.Color Sequence and Overprint Efficiency of Newspaper Printing

      The surface absorption of the substrate actually refers to the absorption of the second color and the last few colors. On newsprint, when printing the first color, the ink film is almost completely absorbed immediately.Color Sequence and Overprint Efficiency of Newspaper Printing

      For the second color ink, the surface characteristics formed by the first color ink film are almost similar to the surface of the unprinted substrate. In this case, even if there is no difference in the tack value of each color ink, a high overprint rate can be obtained in wet overprint printing.Color Sequence and Overprint Efficiency of Newspaper Printing

       Dot gain may be caused by excessive printing pressure or too thick ink layer on the printing plate. In two-color or four-color printing, it may be caused by reverse printing. When printing the next sheet, the ink film of the background color thickens or diffuses after printing because the rubber drum of the latter color is attached with the ink of the previous color. Color Sequence and Overprint Efficiency of Newspaper Printing

       This situation is more serious for magenta ink, so magenta ink is usually printed behind. To reduce dot gain, you can print a special color after the ink that is easy to cause dot gain; Or after four-color printing, print a special color.Color Sequence and Overprint Efficiency of Newspaper Printing

       The ink with the lowest transparency is printed first. Generally, the transparency of yellow ink is the lowest, and the absorbability of newsprint is strong, which improves the printing of wet overprint.Color Sequence and Overprint Efficiency of Newspaper Printing

       Yellow ink is printed first, while dark ink is printed later. It is easy to overcome the problems such as concentration change and registration error.Color Sequence and Overprint Efficiency of Newspaper Printing

        Now the transparency and gloss of yellow ink have been improved. When black ink is dry, it will produce a bronze luster hue, which makes people feel that the color is not pure, and the back printing of yellow ink can overcome this effect. Color Sequence and Overprint Efficiency of Newspaper Printing

           Because the yellow ink usually has a large area and a wide coverage range, the yellow ink printing on the top layer can play the role of glossy surface to destroy the influence of surface light scattering, and has the characteristics of brightening printing products.Color Sequence and Overprint Efficiency of Newspaper Printing

           The color reproducibility of yellow ink is weak. Therefore, the ink film is thicker when printing yellow first. Because the post printing tack value cannot be higher than the previous color ink, yellow cannot be printed first.Color Sequence and Overprint Efficiency of Newspaper Printing

        Another reason not to print yellow first is to avoid dot increase. Because yellow ink usually needs to be printed thick and has a large coverage, especially in full plate printing, if it is printed first, it will change the hue of the substrate surface and increase the possibility of dot increase of other post printing ink.Color Sequence and Overprint Efficiency of Newspaper Printing

          Mainly for the size of the substrate, printing ink with small paper flexibility first is conducive to registration.Different printing color order will affect the final tone, which generally depends on the characteristics of the printed matter.Color Sequence and Overprint Efficiency of Newspaper Printing

         Large area post printing, unless the ink used has high opacity, because the transfer ability of the ink on the paper surface is much better than that on the ink film. If a small area is printed first and then a large area is printed, the overprint part is directly printed on the paper for a small area, and the ink transfer is good, so the overprint effect is good.Color Sequence and Overprint Efficiency of Newspaper Printing

        On the contrary, if you print a large area first and then a small area, although the large area transfer is good, for a small area, the printing ink is all stacked on another color (large area) ink film, and the color performance is poor. For the overall effect, it is not as good as the former.Color Sequence and Overprint Efficiency of Newspaper Printing