Chromatic aberration, also known as color shift, is one of the typical quality ills in the printing process. In the production process, the phenomenon that the printed matter does not match the color of the proofing sample often occurs, or the color of the pattern is superimposed after the overprinting, and the lighter affects the quality of the product, and the whole batch of products is scrapped.

First summarize the causes of color shift and color mixing failures:

1. The yellow, magenta, and blue color dots caused by the irregular plate making operation are too deep or too shallow;

2. The ink color is improperly blended or the three primary inks do not match. That is not the same brand, the same type of ink;

3, the color sequence arrangement is unreasonable, mainly refers to the color sequence arrangement of the multi-color offset printing machine;

4. There is a serious color shift phenomenon in the printed paper itself;

5. Due to the serious hanging on the blanks on both sides of the printing plate, it causes color mixing (common in semi-satellite offset printing machines);

6, other reasons such as: when changing colors, the ink roller is not clean, the paper is not normal, the plate change is not timely, the signer is irresponsible, the ink is not balanced.

For the above reasons, the offset press operator must pay attention to the following aspects:

1. When correcting the ink color, the correct operation should be: after the printing plate is calibrated, the printing paper is used to correct the ink color, and the proof printing sample must basically conform to the printing proof before printing normally;

2. Under normal circumstances, the signer must complete the sample in a short time to reduce the occurrence of chromatic aberration;

3. Correctly master the balance of ink and water, pay special attention to the pH value of the dampening solution. Under the same amount of ink, the small water and small water will also affect the color of the color. The principle of water consumption is not dirty. Minimum liquid supply;

4. According to the quality of the paper, the frequency of cleaning the blanket is determined. If the quality of the paper is poor, and the blanket is not cleaned in time, the color difference will also be caused;

5, to ensure that the paper is normal, each time the paper feed pauses will cause the product to be deep. Therefore, it is necessary to develop a good habit of removing 6-8 pieces of product each time the paper is stopped and printing, so as not to be mixed in the finished product, causing chromatic aberration;

6. If the long version of the product is found, the plate should be replaced in time. The ability of the flower plate to absorb the ink is reduced, which also causes the product to be dark and chromatic.

7. For the products printed on the front and back, we must pay attention to the darkness of the positive and negative sides. We should always compare the ink color with the reverse products to prevent the deeper or deeper the printing, which will affect the quality of the products. For products with cross-page puzzles, it is necessary to arrange as much as possible on the same machine and print the same shift. Otherwise, serious quality accidents will result.

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