Paper wrinkling, overprinting, and ghosting caused by uneven paper
The fibrous tissue of paper has a strong hygroscopicity and it is easy to change its moisture content with the change of the environment humidity and humidity. Then, once the moisture content of the paper increases, the fibrous tissue will exhibit elongation. Conversely, if the moisture content of the paper decreases, the fibrous tissue will shrink. Therefore, this is also the reason why paper has tight edges, curls, ruffles, and uneven paper.
These paper deformations are the main cause of printing wrinkles, misprints, and ghosting failures. The daily production practice shows that if the moisture on the four sides of the paper is excessively dispersed and the middle part is larger than the water on the side, a tight edge will be formed. In the case of tight-edge printing, wrinkling is likely to occur in the middle of the printing area. The solution to this problem is to splash water around the stack of paper, increase the humidity of the environment, and allow the edges of the paper to dampen to restore flatness. If there are conditions, you can use hanging paper machine to hang paper, and splash water on the ground, so that better.
Curl curling is due to the difference in water content between the front and back of the paper, which causes differences in the amount of water on the paper surface, causing curling on the side of the paper with low moisture content due to shrinkage. When the edge of the paper is curled, during the printing process, it is easy to cause wrinkling, misregistration, or ghosting failure because the paper is not fed or the paper edge is bent when the paper is bitten. Printing wrinkles and creases caused by curling of the paper edge generally have a large non-positive oblique shape, and the position of the wrinkle is not fixed. The way to eliminate it is to adjust the curled edge of the paper to make the edge of the paper straight and strong. Ruffles also tend to cause wrinkling, misprints, or ghosting problems. The most common problem is printing wrinkle failure.
The appearance of the lotus leaf is the performance of the moisture absorption and elongation of the paper edge, making the straight edge of the paper edge longer than the middle part, so that the paper edge is loose and the middle is relatively flat. During printing, the wavy paper edge is impressed during the imprinting process. The phenomenon of wrinkling occurs due to pressing. Such wrinkles generally appear on the side of the paper, and the wrinkle is most likely to occur in the trailing parts of printed products. For the paper with flounced edges, the treatment method is: Hanging the paper on the paper to make the water content of the paper surface uniform and consistent with the wetness and humidity of the printing shop, so that the edge of the paper can be restored. degree. To maintain good flatness of the paper, attention should be paid to the control of the quality from the source of the check: First, to maintain the stability of the paper performance, the newly entered paper should not be put into use immediately, it is better to use after a period of time is better; second is to store The temperature and humidity of paper warehouses, paper cutting workshops and printing workshops must maintain corresponding balance conditions and cannot be stored in large disparities to prevent deformation. This is also an effective measure to reduce or avoid printing wrinkles, misprints, and ghosting failures.
