Automatic Printing is the Only Way to Development (3)

Prepress application skills

As we all know, each piece of printed matter must be printed before the design of the main body through the computer color separation, discoloration processed into a negative film, and then plate making and printing, especially offset printing and screen printing negative film production processing is different, offset printing film is positive Anti-words, many times in order to better visual effects may not only be four-tone tone, there are some to use spot colors, and screen printing is more the use of spot colors. Of course, sometimes for the design needs, screen printing on certain specific patterns, there are also used the combination of dot tone and solid color, as well as screen printing and refraction, must use special files for production.

In the combination of offset printing and screen printing, there are many craftsmanship techniques. For example, when the two are combined for printing, the line diameter of the offset printing “10” code is generally 5μm, and the “10” code alignment of screen printing is If the line is not published with a 5 μm diameter, it must be changed to (15 to 20) μm, and the bite edge and pull edge must be the same as the offset, otherwise it will not be accurate.

Many packaging and decoration prints must be covered with a matt film or film (printed on a matte or glossy surface depending on the design needs), and the tension of the corona layer on the surface of the matte film or film must be covered. Above 42 dyne, UV screen printing can be performed on the film surface to achieve the best adhesion.

Offset and coated printing paper, especially thin paper (80 ~ 127) g, after the film is covered, the width of the folio will generally be shortened (1 ~ 3) mm, and the length will be shortened (0.5 ~ 2) mm . In the wet rainy season, the coated paper may also stretch. Therefore, according to the situation of the weather, with the prepared film proofreading, the vertical and horizontal lengths of the film are readjusted according to the horizontal and vertical errors of the “10” code. At present, there are a lot of UV offset printing on the surface after the UV light without the use of coating film, after the combination of screen printing, the effect is better.

Another case is the technique of screen printing and offset printing on transparent sheets (PVC, PET) or sandpaper (PE). PVC, PET sheet with electrostatic serious can not be high-speed printing, need to be carried out in addition to static electricity, such as the use of screen printing semi-automatic flat sheeting machine is better. The PP scrub sheet has very little static electricity and is suitable for high speed printing. However, the thickness of the sheet should be within 60 μm.

General transparent film or frosted film (translucent) are printed in India, so the color sequence should be the opposite of surface printing. Such as the design of some special effects combined with screen printing on the surface of the sheet, that is printed in combination with printing, you can more vividly express the theme of the printed matter. However, we must pay attention to printing, such as the printing pattern is positive pull gauges, then the direction of the bite when the direction of printing the same, but the pull gauge must use anti-pull gauge in order to accurately align.

In the printing of plastic sheets, there is generally no deformation and stretching of the sheet, and it is not necessary to consider the degree of transparency of the “10” code of the sheet itself. On the right, the legend of the "Floral and Snowy Moon" cake box is a double-sided screen printing of 25 μm thick transparent PET sheet. He was awarded the Gold Medal in the 11th Henghui Cup Gold Net Award in 2003, and the Silver Medal in the 2003 Asia-Pacific Screenprint Boutique Exhibition.

In offset and screen printing packaging and decorating printed materials, especially in hardcover books and magazines, the most used is the offset printed film on the matte film, and then on the matte film UV screen printed with local light, through a partial theme pattern mute The contrast increases its visual effects. Of course, there are also dumb oils on the glossy film, which also can achieve the visual effect of muted contrast. Skills in process application must be continuously explored and improved in practice.

In actual operation, due to the slow speed of screen printing and the high cost of ink, each designer and screen printer should try their best to express the best visual effects with the least amount of screen printing. For some of the additional value is relatively high, but must have a variety of special effects are mixed in order to vivid performance of the print, otherwise another matter.

In the case of offset printing with complex screen printing, it is necessary to have a real sample program. Through proofing, defects can be better identified, deviations can be adjusted, color sequence and effects can be corrected, errors can be corrected, and the like can be made more perfect.

The improvement of technology and craftsmanship is endless. Only by continuously improving and improving one's own level in tireless exploration and research can we create more contemporary and progressive ideas. These are some of my experiences in offset printing combined with screen printing in the past ten years. I hope that I can play a role in attracting you for discussion and discussion with everyone. (Finish)