The hottest technology share how to avoid color di

Technology sharing how to avoid color difference in offset printing

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core tip: color difference is also called color deviation, which is one of the typical quality defects in the printing process. In the production process, it often happens that the color of printed matter is inconsistent with that of the proof sheet - 8.2 products should provide sufficient product information, Or the color difference after the overprint of the pattern and picture is also called color deviation, which is one of the typical quality defects in the printing process. In the production process, the color inconsistency between the printed matter and the proofed sample sheet often occurs, or the color mixing fault after the overprint of the pattern and picture, which will affect the product quality slightly, and seriously will scrap the whole batch of products, causing color deviation and color mixing fault, which can be summarized as the following reasons:

1. Yellow, magenta A certain color dot is too dark or too light

this is mainly because the light source intensity and spectrum of the printing plate do not match the photosensitive characteristics of the printing plate, or the exposure time is improper, and the pH value of the developer and the length of the development time are not properly controlled, which may cause the printing plate dots to be too deep or too shallow

2 the ink color is improperly mixed or the three primary colors do not match. That is, it is not the same brand and model of ink

this kind of film must be environmentally friendly. 3. The color sequence arrangement is unreasonable, mainly referring to the color sequence arrangement of multi-color offset press

4 printing paper itself has serious color deviation

5 color mixing is caused by serious dirt on the blanks on both sides of the printing plate (common in semi satellite offset printing machines)

6 the ink roller cannot be cleaned when changing color

7 paper feeding is abnormal

8 version change is not timely

9 those who sign samples are not responsible

10 ink imbalance

in view of the above reasons, the offset machine operator must pay attention to the following aspects:

1 when correcting the ink color, the ink color must basically conform to the sample before printing. One sided pursuit of output, often the ink starts printing when the distance between the ink color and the printed sample is large, which is bound to cause a large color difference between the front and back printing products. The correct operation should be: after the printing plate is calibrated, use the master paper to correct the ink color, and the trial printing sample must basically meet the printing sample before normal printing

2 generally, the signer must sign the sample in a short time to reduce the occurrence of color difference

3 correctly grasp the balance of water and ink, and pay special attention to the pH value of the wetting liquid. Under the same ink volume, large water volume and small water volume will also affect the color depth. The principle of water consumption is to use the minimum liquid supply without getting dirty

4 the frequency of cleaning the blanket is determined according to the quality of the paper. If the quality of the paper is poor and the blanket is not cleaned in time, it will also cause color difference

5 ensure that the paper feeding is normal. Every time the oil pump and Electromechanical group are configured in series with double elastic support, the paper feeding pause will cause the product to be too deep. Therefore, we should form a good habit, that is, take away 6 ~ 8 pieces of products when printing after each paper feeding pause, so as to avoid mixing in the finished products and causing color difference

6 if the printing plate of a long version product is found, it should be replaced in time. The reduction of the adsorption capacity of the stencil to the ink will also cause the depth of the product imprint and form a color difference

for the products printed on the front and back, we must pay attention to the depth of the front and back, and often compare with the ink color of the products on the back, so as to prevent the product quality from being affected by the deeper printing or the lighter printing. As far as possible, the products of cross page jigsaw should be printed on the same machine and in the same shift, otherwise, serious quality accidents will be caused