Explore printing quality problems that are likely to occur in printing

Editor's Note: The printing plate is the carrier of the printing, and the quality of the printing plate directly affects the quality of the printed product. In this article, the author made a simple discussion on the quality of printing plates that are likely to occur in printing.

1. Reticulated lines

Concept: Two or two groups intersect with each other at different angles or lines to display different intersecting reticulations, and the large intersecting reticulates that degrade the image's beauty are called moire.

Cause: The color or the number of lines in the two-color or multi-colored version is inseparable.

Platemaking requirements: Two strong mesh angles must be staggered by 30 degrees, ie 30 degrees and 60 degrees. (In general, 37 degrees and 60 degrees can be matched.) The number of lines generally requires the same network cable. When special lines need different lines, the network lines should be staggered as much as possible.

Printing reason: ink viscosity is not suitable

Solution: When a field version is printed with another netted version, the ink in the field version is generally too thin and the ink layer is not thick enough.

2, water lines

Concept: On ink, the ink exhibits uneven, watermarked print markings.

Cause: The printing ink does not have good fluidity.

Platemaking improvement measures: change the screen angle and increase the gap. However, the ditch cannot be too large; otherwise, unevenness will easily occur during printing.

Printing solutions: 1 increase the viscosity of the ink; 2 increase the printing speed; 3 correct the printing tension.

3, with the network color deviation

Concept: Two or more colors of the same pattern exhibit different hues when printed.

Cause: The two-color or multi-color version of the network cable and the screen angle are exactly the same. When printing, some dots completely coincide with each other, and some dots are staggered, resulting in inconsistent visual colors.

It is easy to produce shades of gray, purple, brown, and similar color overlays that are similar to the mesh color hue.

Platemaking improvement measures: When faced with easily biased hue, try to avoid using the same mesh.

Printing Solutions Improve Overprint Accuracy

4, out of the point (in the water profile)

Concept: 65-80% of the net into the phenomenon of uneven spots when printing.

Cause: Due to the ink's own fluidity,

When 65-80% of the nets were printed, some of the outlets were linked together, and the other outlets were not connected, resulting in uneven printing.

Out of a relatively serious hue: dark purple, brown, dark green, dark red and so on.

Platemaking improvement measures: 1 better ink; 2 adjust the ink viscosity; 3 adjust the blade angle or pressure; 4 improve the printing speed.

5, blocking version (net plug)

Concepts: 1 In the printing process, the printing ink transfer rate is continuously decreasing; 2 The ink blocked in the plate during the second printing cannot be dissolved.

Causes: 1 The ink is too clean; 2 the net pit is too small, the ink is not easy to transfer; 3 the inner wall of the net pit is not smooth.

Edition improvement measures: 1 high network line to use low network engraving; 2 shallow network into a larger; 3 re-chrome replating, to ensure that the inner wall of the pit clean.

Printing solutions: 1 Change the slow-drying solvent; 2 Improve the printing speed; 3 Reduce the viscosity of the ink; 4 Clean the plate roller quickly after each printing; 5 Check whether the blower blows the wind onto the platen roller.

6, corrosion (chrome)

Concept: When the chrome surface of the roll is exposed to corrosive liquids, gases, or unqualified solvents such as acids and alkalis, it will soon start a chemical reaction and form a rust on the chrome surface, ie, corrosion.

Preventive measures: 1 After each printing, use a solvent (preferably a day of water) to clean the surface of the roller in a timely manner; 2 Dry the plate with a clean, soft cloth, and do not leave fingerprints; 3 Clean up with a brush. The low volatility light motor oil is evenly coated on the surface of the printing roller. Care must be taken not to use waste oil. Such as the use of special anti-rust oil effect is better; 4 with a film (such as the use of waste printing film, be sure to face the ink out) the oiled version of the roll wrapped, and then wrapped with corrugated paper, vertical or put up with a shelf Store in a room that is ventilated, dry, and protected from direct sunlight. 5 Storehouses should not be placed on the first floor and should be kept away from acids, alkalis, and other items.

7, drawing (knife line)

Concept: The unscratched ink of the squeegee draws linear marks on the non-graphical or shallow part of the plate roller and transfers to the film. It also refers to the phenomenon caused by the lack of squeegee.

Causes: 1 Bad squeegee quality or notch; 2 Ink particles coarse or high viscosity; 3 Scraper angle or pressure is not appropriate; 4 version of the roller chrome surface is rough or poorly polished; 5 version of the roller slightly, oval degree Too big or poorly balanced.

Remedy: 1 Check whether the squeegee has a gap, use sandpaper to grind or replace; 2 Filter the ink to reduce the large particles in the ink; 3 Polish the surface of the roller with sandpaper; 4 Check the slightness, ellipticity and dynamic balance of the roller ;5 re-polished or re-plated chromium replating.