How to solve the problem of book printing with white dots?

How to solve the problem of book printing with white dots?



1.Powder of printing materials

Reason: the performance of this kind of problem is that the number of white spots is not large and the position is not fixed. Different from paper wool and paper scraps, the powder drop of printing material is due to the lack of its own surface strength, resulting in the ink adhering to the small powder particles on the surface of printing material, thus forming a white spot. With a magnifying glass, there is almost no ink in the white spot.

Solution: reduce ink viscosity. If the effect is not obvious, qualified enterprises can also print a layer of primer ink or desalting agent on the printing surface to solve the problem of powder drop. Since the primer ink and desalting agent can cover the surface of the printing material, which is equivalent to scraping a layer of putty on the surface of the printing material, the printed ink is actually printed on the primer ink or desalting agent coating, so as to effectively reduce the printing white spots caused by the powder drops of the book printing material.

2.Inhomogeneous material

Cause: sometimes the surface of bearing material is uneven, which will also lead to printing white spots. For this reason, the main form of printing white spots is that there are many white spots and dense white spots.

Solution: for some large on-site pattern labels, the problem of white spots can be solved by printing twice. Generally speaking, printing primer ink can be used to increase the smoothness of the surface of printing materials to solve the problem of white spots.

3.Paper hair or dust

Printing white spots caused by dust in the printing environment are usually obvious and fixed in position. However, the white spots caused by paper hair are not very regular. Generally speaking, there are not many white spots at the beginning. After a period of printing, there will be more and more white paper, wool and paper scraps on the drum of the machine.

Solution: if there is more dust in the printing environment, the workshop needs to be cleaned. The effective way is to spray water and mop the floor. If the printing white spots are caused by wool and paper scraps on the paper, dust removal cloth can be added to the feeding part of the machine to reduce the generation of white spots.

4. Causes of static electricity

Cause: some film adhesive materials will generate static electricity in the book printing process, which will push away the ink and lead to white spots. The white spots caused by this phenomenon were observed under the magnifying glass, and the explosion effect was found around the white spots. At the same time, it is obvious that there will be strong static electricity on the surface of printing materials during the printing process, and the first-line printing operators often get an electric shock.

Solution: install electrostatic precipitator on the printing press. For book printing companies without conditions, humidifiers can be installed next to the machine to increase the humidity of the local environment, and can also play a good role in removing static electricity.

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