Compared with coated paper, offset paper has poor surface smoothness, poor penetration of the binder in the ink, and ink tends to accumulate on the surface of the paper. Sometimes the surface of the ink is oxidized and conjunctiva, but it cannot be completely dried. Therefore, when the reverse side of the offset paper is printed, since the front side printing ink is not completely dried, the ink will fall on the impression cylinder at the time of the back side printing, and the ink layer on the impression cylinder will build up and increase with the increase of the number of prints. The pressure generated by the text is getting bigger and bigger. Eventually, the frontal picture becomes false and the imprinting is false. If sampling is not checked often during printing, a large amount of waste products will be produced, causing unnecessary waste.
Solution
When the ink is completely dry and the back is printed, it takes a long time and daily production is impossible. Take the method of frequently cleaning the impression cylinder, so that the accumulation of the ink layer should not be too thick, reduce the impact on the front image, but also can basically solve the problem. Normally, this issue will not appear below 3000 yen. The more the number of prints, the more obvious. In order to avoid such problems, it is necessary to take more samples and check more.