Case analysis of ink crystallization failure during printing

The so-called "ink crystallization" refers to the improper control of the printing interval between two colors of ink, the first printing ink has dried solid before the ink is overprinted. Due to the low viscosity of the dry ink layer and the poor wetting of the ink, it is difficult for the next color ink to adhere thereto.

In general, this phenomenon occurs in the ink overprint of a monochrome offset printing press. In order to avoid ink crystallization failure, the ink layer that is printed first generally must have the following conditions:

(1) Maintaining a certain degree of wettability, it can be wetted and adhered by the ink after printing.

(2) Maintaining a certain degree of tackiness, and the adhesion of the ink after printing is greater than the cohesion of the ink after printing.

(3) Control the amount of desiccant (dry oil) used.

If there is a problem with the “ink crystallization” printing process, the surface of the printing ink may be rubbed with fine gauze to make the surface of the ink film rough, and the capillary suction force is increased to increase the ink overprint effect. For the “ink crystallization” printing products with large printing format and large batch volume, it is best to superimpose the high-viscosity oil varnish on the surface of the ink, and use its strong adsorption to adhere to the dry ink layer, and then use it. For the media, the post-printing ink adheres well.

[Case 2-11]:

A factory uses a monochrome offset press to print 100,000 flower calendars. Its pattern is a red peony, the paper is 128g/m2 double copper, and the ink is a quick-drying light. When the yellow and the magenta were printed, when sky blue was overprinted, many blue inks were found to be difficult to adhere to.

[case analysis]:

This is a typical phenomenon of "ink crystallization". The reason for this phenomenon is that the paper used is poor in ink absorption, the second is the use of a quick-drying glossy ink, and the third is the amount of white paper that is put in too much. Therefore, in view of this situation, special attention should be paid to the proper control of the amount of white paper to be delivered by the single-color offset printing press, and the appropriate color conversion sequence.

Treatment method: Because of the large number of prints, it was necessary to cover the oil once before printing. Remember that you must plan well when you next print.