Reasons: Insufficient film density; improper flat-screen plate-making process; quality of printing paste.
The negatives are made by computers. The higher the density of the film, the better the coloring effect. If the blackness is insufficient, the shading effect will be poor, and the ultraviolet rays will easily penetrate and cause occlusion. The haze of the negative film is low. If the haze is high, the UV transmission is blocked, and the exposure time needs to be extended to complete. It is easy to cause the exposure time to be too long and cause blocking.
Solution: Improper operation of flat film solidification process will cause blockage. When developing, it should be considered that the ultraviolet light is transmitted from the screen printing surface to the scratching surface. The printing surface is fully luminous and can be washed with water under high pressure; the crosslinking degree of the scratching surface is less than the crosslinking degree of the printing surface, and the film is soft. Press the residual slurry to flush the sieve holes to prevent the residual slurry from blocking the sieve holes. Before curing, the curing agent should be re-exposed to make the film have sufficient photosensitivity and re-coated.
When printing, the used paste contains impurities or insoluble particles that block the mesh, so that the color paste cannot be scraped out of the mesh, so the paste should be filtered out before use. In order to prepare paint binders, good quality binders and compatible thickeners should be selected. Don't scratch the conjunctiva too quickly.