The most popular screen printing faults and Counte

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Silk printing faults and Countermeasures

v. pinhole

pinhole phenomenon is the most headache for staff engaged in silk printing. If it is the printing of opaque objects such as billboards and thick paper, such small holes that are not easy to observe are generally not a problem. However, pinholes are not allowed to be generated when precise printing is carried out on aluminum, glass and propylene plates, which need post-processing and corrosion processing. In addition, there are many reasons for pinholes, many of which cannot be explained at present, and some of which are quality management problems. Pinhole is one of the most important inspection items in printing product inspection

① dust and foreign matters attached to the plate. During plate making, some sol will be mixed in during water washing and development. In addition, during emulsion coating, China has not seen any strategic decision at the national level on strategic minerals, important advantageous minerals and severely scarce minerals. The international influence of dust mixed into China's plastic machinery industry continues to increase, and pinholes will be generated when it is attached to the silk. These polyurethane base plates are about several hundred grams each. During the test, if you pay attention to the inspection, you can find them and repair them in time. If dust and foreign matters are attached to the plate, blocking the opening of the plate will also cause synthetic pinholes consistent with the alignment accuracy. Before formal printing, if you use ink absorbent paper and print several sheets, you can remove the dust from the plate

② cleaning of substrate surface. Aluminum plate, glass plate and propylene plate shall be pretreated before printing to make their surface clean. After the substrate is pretreated, it should be printed immediately. In multicolor printing, the method of rubbing with alcohol before printing is generally adopted. In addition, semi-automatic and full-automatic ultrasonic cleaning machines can be used. After pretreatment, dirt such as grease can be removed, and dust attached to the surface can also be removed

the detergent used in the cleaning machine is often mixed with broken fiber. This detergent is dissolved in alcohol. When cleaning the surface of the substrate, it often forms a thin surfactant film, and pinholes will occur when printing ink on the film. Therefore, special attention should be paid to the use of cleaning agents and alcohol. When the substrate is handled by hand, the fingerprint of the hand will also be attached to the printing surface, and pinholes will be formed during printing

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