Reasons for the low density of printing in the field

What is the reason for the low density of printing in the field? In fact, this problem is believed to be understood by all of us, but it is somewhat difficult to specifically say that it is ugly. After consulting the technical staff of a domestic offset printing manufacturer, the technician gave his own opinion and repeatedly stated that the secondary viewpoint only represents personal opinions. The following is the full text of the reply:

I think you are referring to offset printing.

For offset printing, there are mainly the following reasons:

1, PS version of the body, the network point on it is not true.

This may be due to the fact that the dots on the film do not have sufficient darkness. One expert suggested that the black field density value should be 3.5. Otherwise, when printing, the dots will pass through the light, causing the exposure of the photosensitive layer. The dots on the printing plate are not solid, and the dots drop when printing.

If the film is no problem, it is the problem of exposure and plate-making. If the exposure time is too long or the ratio of the liquid medicine is not proper, it will also cause the printing plate to have an unobtrusive Internet access point and drop the dots when printing.

2, printing machine reasons.

The influencing factors in this area are more complicated:

(1) The embossing cylinder is worn or peeled, resulting in poor contact between the embossing cylinder and the paper, making the dots misleading.

(2) In the printing, the printing speed suddenly increases greatly and the printing pressure does not increase correspondingly. It also makes the prints lighter and the dots are not true. This is because when the printing speed is increased, the contact time between the plate and blanket, the blanket and the printed sheet corresponding to each other is reduced, and the possibility of incomplete contact between the printed surfaces is increased. The transfer of images and texts is incomplete. The dots are not true and the ink is gray.

(3) Improper adjustment of fountain solution and ink.

(4) Ink rollers, water rollers, blankets and other reasons (see the article below)

3, the reasons for the paper.

If the paper itself is not smooth enough, the impression cylinder is in poor contact with the paper. Or because of the poor ink absorption of the paper, it can also cause the network points to be false.