Problems in the process of four-color printing for monochrome printing

1. Arrangement of color sequence Printing color sequence, if not properly arranged, may cause adverse effects such as reverse printing and color mixing. At the same time, attention should be paid to the color sequence of the proofing so that it will not deviate too much from the proofs. If you don't have proofs, you should decide according to the color of the original. Which color the original is biased to, which color should be arranged in the last printing.
2. Overprinting problems can not be overprinted, and the printed products will be distorted so that they cannot be accurately restored. The following points should be noted when registering.
(1) Overprinting rules should be adjusted well before start-up printing, change color, change version halfway, do not move the front gauge, and solve with versioning. In addition, the front gauge and side gauge stopper should be at an angle of 90°.
(2) It is not permissible to adjust the feeding and dentition of the transfer cylinder during printing. If it is necessary to adjust, the front and rear semi-finished products should be separated.
(3) When the first color is printed, the pressure can be adjusted to a small point, and the roller gap is generally 0.05mm. The purpose is to reduce the dot size to compensate for the large size of the graphic image caused by the elongation of the paper, so as to achieve accurate overlay printing.
(4) Strictly control the surface water of the printing plate. The amount of water is not based on paste version.
(5) Try to prevent the paper from being skewed when feeding.
(6) Adjust the paper bristle brush and adjust it easily.
3. Problems with inks (1) Printing the same batch of products should use the same manufacturer's ink.
(2) The amount of ink cannot be large or small.
(3) The use of additives should be appropriate.
(4) The ink should not be too thin. Too thin the ink will cause the back of the sticky. Ink color is uneven, the coloring power is reduced, the linking material is infiltrated too much, the printed matter is not easy to dry, easy to pulverize, ghosting, bad brightness and so on.
4. Problems with paper (1) Smoothness. Paper with high smoothness has a good gloss and contact elasticity with the blanket is also good.
(2) Whiteness. Whiteness affects the contrast of printed images and the proportion of high-profile colors.
(3) ink absorption. The lower the ratio of the binder in the paper coating and the pigment in the ink, the better the paper absorbs the ink.
In short, when overprinting four-color products with a monochrome machine, every aspect of printing should be noted.