How to print a large area of ​​offset printing

If you want to use the offset printing process to print a large area of solid ground color. On the one hand require high precision printing machine, and the need to use suitable process methods.

1. Try to avoid thin lines in spot colors

The thickness of the ink layer for color mesh printing is not suitable for printing large-area background colors, especially when the surface of the substrate is not smooth enough, it will give the impression that the ink color is not thick enough and uneven.

Spot color solid background printing generally needs to increase the amount of ink supply. The thicker ink layer on the layout will inevitably increase the probability of the ink expanding to the blank part, so it is necessary to avoid extremely fine ground solid colors during pre-press design And small strokes; if there are small characters, try to use bold fonts because the strokes of bold fonts are relatively thick and not easy to paste.

Second, the background color of the second overprint is better

If there is both a black background and a color mesh image on a layout, then the black version must have both a large area and a mesh image, which determines that the black ink cannot be printed too thick. In the case of not specially making a black background color version, in order to achieve a thicker visual effect of the black background color, you can add about 40% of the flat screen to the corresponding part of the black background color of the blue version, because the black ink is overprinted in the blue color It's still black on the flat net, and the result is that the ink layer becomes thicker. In this way, it is possible to obtain a more satisfactory thickening effect when the black ink is not very thick.

In addition to the color image, some products need to print some dark spot color background colors, such as scarlet background color, dark blue background color, etc. At this time, you can add flat screen printing to the corresponding part of the background color on a certain color version Make a primer and overprint spot colors on it. If printing a red background, you can add a suitable number of flat screens to the parts corresponding to the red background on the magenta version; if printing a dark blue background, you can add the appropriate number of parts to the dark blue background on the blue version Flat net.

The advantages of large-area background color overprinted by two printings are: on the one hand, under the control of the thickness of the ink layer of the background color plate, the overprinted ink layer is thicker; on the other hand, it can greatly reduce the ink skin and paper powder , Streak and other adverse effects on the printed screen. For example, when the black background color is printed only once on the white paper, due to the influence of paper scraps, ink skin, or other reasons affecting the ink transfer during the printing process, very obvious spots and trachoma will appear on the black background color. If the black background color is overprinted on the cyan flat screen, even if the black ink layer has trachoma, since the exposed is no longer the white paper base, but the cyan flat screen ink layer, compared with the black self-strong contrast, the black-cyan contrast It's less obvious.

3. Typesetting is as good as possible for ink distribution

Try to avoid the middle of the solid part with an elongated blank skylight along the rotation direction of the drum. Due to the limited ink-crossing capacity of the printing press, the elongated skylights along the direction of rotation of the printing cylinder will cause the darkening of the upper and lower ends of the skylights during printing, which seriously affects the appearance of the picture. If the skylight is not within the shape of the finished product, consider adding it to the same ground as the surrounding area, or if possible, rotate the entire pattern by 90 degrees. In the production of printing plates for packaging products, since multiple patterns are often stitched together, slender blanks often appear at the joints. Such blanks should be filled with the same solid areas as possible. Although some ink is wasted, it is conducive to uniform ink color.

About Liyang

Liyang Paper Products Co., ltd is a factory and trade company located in Dongguan, China. Specialized in producing paper printing service, such as gift box,paper box, paper bag, book printing, notebook, folder, jewelry boxes, paper tags, jewelry tags,sticker,envelope, etc.
Custom made base on your design is welcome, feel free to contact Liyang printing with your full details.
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