Color difference in printing, also known as color deviation, is one of the typical disadvantages in the whole process of printing and packaging. In the process of processing, it often produces the situation that the color of the printed matter does not match the color of the proofing sheet, or the mixed color fault after the overprint of the pattern design interface, which may endanger the product quality at least, and seriously scrap the whole batch of products, just like when we buy things on the Internet, Merchants will always note "there may be color deviation, please take the color of the real object as the standard" in the product picture.
1. The dot of yellow, magenta and cyan is too deep or too light due to the nonstandard actual operation of printing and plate making.
The key here is that in the whole process of drying the printing plate, the compressive strength of the ink printing light source, the mismatch between the spectrometer and the light sensing characteristics of the printing plate, or the exposure time is not good, and the pH value of the developer and the length of its development time are not properly grasped, which will lead to the printing plate dot too deep or too shallow.
2. The color of printing ink is poorly prepared or the printing ink of three primary colors does not match.
That is, it is not the same famous brand and the same printing ink. For the goods packaged and printed on the front and back, we must pay attention to the depth of the front and back, and often compare it with the light ink of the goods on the back, so as to avoid harming the quality of the goods by printing heavier or lighter. For goods with jigsaw puzzles, try to distribute them in the same machine and equipment, and package and print them in the same train number, otherwise, serious quality accidents will be caused.
3. Color sequence allocation is unscientific, which mainly refers to the color sequence allocation of multi-color offset press.
4. Packaging and printing paper itself has serious color deviation.
5. The blanks on both sides of the printing plate are seriously dirty, resulting in mixed color conditions (mostly seen in semi satellite offset printing machines).
To properly grasp the balance of ink painting, we need to pay attention to the pH value of the wetting liquid. Under the same ink volume, more water and less water will harm the depth and lightness of the tone. The principle of water consumption is to use the minimum liquid supply without getting dirty.
6. When changing colors, the ink roller cannot be cleaned.
Determine the frequency of cleaning the blanket according to the quality of the paper. If the paper quality is weak and it is not cleaned immediately, it will also lead to color deviation.
7. Abnormal paper feeding.
Make sure that the paper feeding is normal. Every time the paper feeding is interrupted, the color of the commodity will be darker. Therefore, we should cultivate a good habit, that is, remove 6 ~ 8 pieces of goods when packaging and printing after each paper feeding interruption, so as to prevent mixing in the finished products and causing color deviation.
8. The version change is not immediate.
If the printed version of a long version commodity is found, it should be replaced immediately. The reduction of the ability of the stencil to absorb printing ink will also lead to the depth of the impression of the commodity and color deviation.
9. The signer evades responsibility.
Generally, the sample signing must be completed in a short time to reduce the color deviation.
10. The ink brush is unbalanced.
When calibrating the light ink, it is necessary to ensure that the light ink foundation conforms to the sample before printing. One-sided emphasis is on the production volume. Generally, printing starts when the ink color is far away from the printing sample, which is bound to cause a large color difference between the front and back printing products. The proper practical operation should be: after the printing plate is calibrated, try the master paper to calibrate the light ink, and the trial printing sample must be basically in line with the printing sample, then everything can be packaged and printed normally.