The flatness of paper, not only affects the performance of paper, but also directly affects the quality of printing. Due to the serious unevenness of the paper, the paper surface will be wrapped and present a "seersucker" shape, so it is inevitable to have poor leveling and quality problems in printing. Generally, the paper with poor uniformity has uneven light transmission when viewed from the light source, even in the shape of "cloud flower". The uniformity of this paper is poor, the surface smoothness is relatively poor, coupled with uneven tightness, ink acceptance and absorption will produce a lot of unevenness, such unevenness will interfere with the uniformity of the printing screen, reduce the quality of the printed matter.
In the field part of printing, there are sometimes slight unevenness. This kind of non-uniformity is mainly the non-uniformity of concentration, but also the non-uniformity of luster. The main reason for this unevenness is that the paper absorbs ink unevenly. This absorption characteristic is closely related to the uniformity of paper. The uniformity of paper is poor, the density of fiber distribution is uneven, and the difference of tightness is obvious, so the ink absorption speed and ink absorption speed will be different, so it is easy to produce the phenomenon of uneven printing surface concentration and gloss.
Similarly, the flatness of the coated paper also affects the quality of the printed matter. For copperplate paper, the part of directly absorbing ink is coating, but when the uniformity of base paper is poor, it will cause the phenomenon of uneven penetration of coating adhesive to base paper layer and uneven ink absorption of natural coating. In addition, the uniformity of the original paper will also lead to uneven coating in the process of coating, especially when there is a great correlation between the uniformity of the scraper coating and the consistency of the original paper, so the original paper often leads to uneven uniformity of the film absorption ink.
Other paper surface defects and defects, such as creases, stains, wrinkles, dust, wet spots, etc., are self-evident to the quality of printed matter.