1. gelation

Phenomenon: due to improper storage or improper use of ink additives and solvents, the ink loses fluidity and solidifies into colloid.

Solution: store the ink tightly in a cool and ventilated environment, and use special auxiliary agents and solvents. In addition, it is also necessary to check whether other inks are leaked. Different inks should be strictly confirmed before use.

2. Fuzzy contour

Phenomenon: the high-profile part of the print is blurred, the dot is false and the tone is lost. The quality of printing plate is not high, the contact between printing plate and ink roller is too tight, the viscosity of ink is large and the ink returns thick, the ink dries too fast and the mixing is poor.

Solution: the backing plate should be even and flat, the printing pressure should be adjusted, the water alcohol should be mixed reasonably and stirred evenly when adjusting the ink viscosity, and the ventilation device should be adjusted. Do not blow onto the ink roller. And improve the machine speed, scrub with water containing monoethanolamine or add 0.2% dimethyl silicone oil or increase the proportion of coupling agent.

3. Light ink

Phenomenon: the ink color is light and can not reach the ideal color concentration. The main performance is that the ink concentration of printed graphics and texts on paperboard is light, the tone is dim and not bright. If the viscosity of the ink is too low, it is mainly caused by the replacement of the original ink.

Solution: the ink should be fully stirred before use. If the ink quality is found to be poor, replace the good ink and check the ink transfer effect. If the transfer is poor, check the factors such as roller, printing plate and paperboard.

4. Ink foaming

Phenomenon: too many bubbles in water-based ink will lead to white spots, sand holes, water marks and other phenomena on the surface of printing products. It is mainly due to the poor foam inhibitor of the ink system, insufficient ink circulation, too much water, too much pump circulation, air leakage of the pipe, and too thin ink.

Solution: properly add defoamer (0.2% or mix internal and external plasticized defoamers) to reduce the circulation of the pump and supplement new ink so that it will not be excessively diluted. Check the pipe to prevent air leakage.

5. Poor drying

Phenomenon: poor drying of printed matter, too fast or too slow. The viscosity of the main water-based ink is too high, the edge of the edge trace is expanded, the drying of the water-based ink is poor, and the paper absorption is poor.

Solution: first check whether the dryness of the ink is appropriate. It is best to use fast drying ink. Check whether the viscosity of the ink is too high. If the viscosity is too high, further dilute the ink; Check the absorption performance of the paperboard. If the absorption performance is too poor, replace the paperboard with good absorption; Check whether the imprint edge is enlarged. If the enlargement is caused by improper printing pressure, adjust the printing plate pressure or replace it with a new one.