[Chinese Packaging Network News] In the larger offset printing plate surface, there is a small area of ​​the printing area of ​​one color or a few colors, and these graphics are often some trademark or iconic patterns or texts, and the hue accuracy and ink color The consistency requirements are more stringent. The ink used in these small layouts is almost zero. When printing, especially when printing with domestic monochrome or multi-color offset printing presses, there will be a lot of failures, mainly as follows.

(1) Since the layout uses a small amount of ink, the ink fountain is almost completely closed and the amount of ink is too hard to control. Under normal circumstances, the amount of ink is likely to be too large. If the ink fountain is adjusted to reduce the amount of ink, the amount of ink may be too small. Repeated adjustment of ink fountains in this way will result in serious inconsistencies in the color of the ink of a batch of prints. Sometimes even the same print, there will be two or more of the same graphics ink very different.

(2) Because the layout uses a small amount of ink and the machine is running at a high speed, the two rollers will inevitably appear as “dry rollers”, ie “drying”.

(3) The layout uses a small amount of ink, resulting in almost no new ink added in the ink path, but the layout water supply needs to be “continuous”, so that under the action of shear force, the ink is heavily emulsified, and the layout is easy to produce “floating”. "In order to make the layout clean, we have to increase the amount of water, so that the ink emulsification is even greater. This forms a vicious circle of repetition, the ink is more difficult to control, and it can also lead to the occurrence of false impressions of small patches and even the phenomenon of “sticking back”.

During the printing of a batch of alcoholic beverage boxes, it was printed on a whiteboard paper with a width of 340mm x 880mm and six colors. Most of the colors are large in area, and there are even full-size versions. The blue version is extremely small, with only a few dots and two trademark patterns about 4mm in size. In order to avoid the above failures, the paper format was changed to 360mm x 880mm, so that the material is still open 3, and does not waste raw materials.

During printing, a 30mm x 880mm solid color bar is printed outside the effective layout of the blue plate, which is a large area of ​​the paper. Although some ink is wasted during printing, the ink is easy to control. Subtle changes were clearly observed on the "color bars" and ink emulsification was successfully avoided, thus ensuring print quality.

In addition, some similar jobs do not add “color bars” during plate making, but we cut the “red film” or red paper into different widths such as 20mm, 10mm, or 5mm according to the size of the printing paper when making PS plates. Sticking to the outside of the film's effective layout is also successful.