The so-called "watermark" is the trace caused by some photosensitizer and developer impurities on the surface of the screen after the batch screen printing plate is developed and baked. Because the marks are not obvious, it is difficult for the operator to observe with the naked eye. When printing on the machine, it will show "no ink leakage" or "bad ink leakage" and other printing failures around the traces.
In the production process of the screen version, the printing plate is generally washed with tap water. If the screen printing time is too long or the water flow is too fast during the processing, the printing effect of the screen pattern is likely to be distorted, the printing resistance is low, and the printing failure of the screen is large area such as ink leakage; When the water flow is slow during washing, it is easy to cause "watermark" failure. In order to prevent the phenomenon of "watermarking" on the screen, and to improve the printing durability of the screen, it is very important to grasp the development and development of the fire.
The development and rinsing operation method to prevent "watermark" is: after the exposure of the screen, the two sides of the printing plate are fully wetted with water quickly. The photosensitizer shall prevail. After fully wetting the plate surface, adjust the water flow speed a little, and only rinse the non-printed surface of the screen, until all the unexposed sensitizer (non-printed pattern) flows down. Then place the screen vertically for a while (about 3min ~ 5min). After finishing, put the screen into the oven. After thoroughly drying, the "watermark" on the screen will disappear.
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