The adverse effects of outlets on offset printing and solutions
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The expansion of outlets does have an adverse effect on offset printing. So how do you control the expansion of outlets? We will talk about specific operational measures from the following aspects.
1. Master the exposure time of offset printing
Controlling the exposure time, development time, developer humidity, and concentration ratio is one of the ways to reduce the dot gain. The four-color film of the color separation is transferred to the printing plate through the printing plate, and the dot size expansion is required to be as small as possible, 3% to 5% of the dot is not lost, 5% of the dot is not enlarged, and 95% to 98% of the dot is not Paste plate, the dot is strong, the point particle circle is neat, the dot has no white point and burr edge, and the tone level is rich and clear. This requires accurate preparation of the PS version of the developer, according to the formulation ratio of the specification, the exposure time is controlled by the gray ladder and the printing signal strip. After the printing plate is exposed, the magnifying glass is used to check the scale and the magnifying glass with 5-10 times. The signal bar level loses the situation of paste and dot enlargement.
2. Reasonable choice of lining material and printing pressure
Offset printing is an indirect printing method. The rubber intermediate roller is required to transfer the printing plate to the surface of the paper. The blanket and its lining are the intermediate medium for graphic transfer. There is no printing pressure without the lining. By adjusting the thickness of the offset lining of the offset printing machine, the optimal printing pressure can be obtained, and the uniformity of the ink color and the clarity of the dot of the printing product can be enhanced. The printing pressure is obtained by adjusting the thickness of the lining and the center distance of the roller. The pressure should be based on the premise that the printed product has strong dot, clear image, bright color and light and dark, and the smaller the applied amount, the better the control dot is expanded. Deformation, adjusting the exact printing pressure is very critical. Accurately calculate and measure the thickness of the blanket cylinder liner with the micrometer in the work, adjust the center distance of the two rollers, and uniformly use the minimum printing pressure within the allowable range of the dot enlargement.
3. Control ink and water balance to reduce dot gain
Control the ink and water balance to improve the quality of printed products. It is recommended to use as little moisture as possible on the premise of not being dirty or paste. Ink balance is also a standard for measuring the technical level of offset printing. Only when it reaches the ink-balanced paper, the telescopic deformation is small, the overprinting accuracy is high, the color is bright, the color tone and the hue can match the depth of the ink of a batch of proofs, and the printed dots are round. It is strong. During offset printing, avoid large water and large ink, and the ink layer is too thick to spread outward. The small dots are not lost in the 3% to 5% bright adjustment area, and the 5% intermediate adjustment points are not enlarged, not stretched, and the dark adjustment area 95%-97% of the large outlets are not ambiguous. The control standard of the ink quantity is as follows: the graphic network dots are solid and clear, and the ink color hue is accurate, and the amount of ink is used as little as possible.