Before the photosensitive resin is coated, a pretreatment of the screen is performed to degrease the screen or remove dust that may adhere to the screen, and the screen and the photosensitive adhesive are easily adhered. The method is to use 20% caustic soda or neutral detergent. When cleaning, use a soft brush to gradually apply the cleaning agent from the center to the surroundings. After brushing evenly on both sides, use plenty of clean water to wash the remaining chemical substances on the screen Plate .

The effect of pretreatment can be judged by observing the formation of the water film on the screen when the screen is immersed in water. That is, the screen is erected. If the water film on the screen flows uniformly and the water-free beads agglomerate, the pretreatment requirements are met. The purpose of the pretreatment is to prevent the defects of the detachment of the photosensitive layer from occurring after the printing plate is used.

After the pretreated screen plate is dried by natural drying or hot air below 40°C, the photoresist can be coated.
Source: China Screen Printing and Imaging Association