1. A basic requirement to achieve perfect image reproduction is that the quality of the transparent positive film is better, that is, the edges of the dots must be neat and opaque. The color separation sheet is in the same color scale as the printing ink used.
2. The positive film is placed on the glass plate, and then exposed. The stretched screen is placed on the positive plate and parallel to the image axis. If moire appears, rotate the screen to the left or right until the moire disappears, usually by 7 °. Areas prone to moire are located in the direction of the screen mesh and at the intersection of the screen. The main and darker colors cause more moire problems.
3. For four-color printing, the same size and stable aluminum screen frame should be used, and the screen frames used should be the same type and type of screen. The use of dyed screens helps to eliminate moire. The tension on the screen should be uniform and the tension of the four screens printed on the four screens is the same.
4. The ground squeegee is very important for high-quality printing. The Shore hardness of the blade is about 70. The squeegee should be set at an angle of 75 °. If the angle of the squeegee is adjusted too flat, the printed image may be blurred. If the angle is adjusted too steeply, the danger of screen printing image deformation is great.
5. The ink return knife should not be installed too low. If this is the case, the film plate will be filled with excessive ink, and the printed matter is easily blurred and dirty.
6. Mesh tone images are printed with high-viscosity inks. The finer the screen, the thicker the ink.
7. Using UV ink, the shade range of the mesh-shading picture should be selected from 5% to 80%, and the Shore hardness of the squeegee should be 75. In order to prevent UV inks from getting dirty during color overprinting, it is recommended to print in the cyan, magenta, yellow, and black color sequence. When using UV ink, the screen thickness should not exceed 5um.
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