Generally speaking, during gravure printing, only 1/3-2/3 of the ink in the plate mesh is transferred to the substrate. If the residual ink solidifies instantly before leaving the printing material and entering the ink tank, and then comes into contact with the ink scraper before being dissolved by the solvent in the ink tank again, the ink transfer rate will gradually decrease. Ultimately, it leads to plate blockage, a decrease in the amount of transferred ink that cannot cover the surface of the printing material, resulting in the appearance of spots on the printing paper.

　　1. Workshop environmental issues, where the temperature is too high, causing the ink to dry too quickly, resulting in clogging problems.

　　2. Ink viscosity is too high, printing speed is too slow, causing ink drying speed to be too fast, resulting in clogging.

　　3. The problem with the embossing roller is that dirt (such as dust, ink, etc.) on the surface of the embossing roller or damage and wear on the surface of the embossing roller can cause poor ink transfer during printing, resulting in the problem of printing blocks.

　　4. Poor surface tension treatment of the printing material results in ink transfer failure during printing.

　　5. In shallow ink transfer plates, a too hard angle of the ink scraper can also cause poor ink transfer in shallow layers.

　　6. Quality issues with the plate roller, such as shallow highlights in the electrical distribution diagram or hanging mesh, especially in surface printed products where the electrical distribution diagram and hanging mesh are not deep enough.

　　During the plate making process, there may be defects on the inner wall of the mesh holes, surface defects left by chrome plating, or burrs generated during grinding due to process and other reasons. These factors will all lead to plate blockage, resulting in insufficient ink coverage and defects such as lost dots and incomplete printing.

　　Solution

　　1. Control the environment of the printing workshop, requiring an indoor temperature of 18-25 ℃ and a relative humidity of 55% -75%. When the indoor temperature cannot be improved, a slow drying agent can be added to the solvent appropriately to reduce the ink drying speed.

　　2. Reduce the viscosity of the ink appropriately. If the viscosity is too high, the solvent content in the ink will be relatively low, making it easier for the ink to evaporate and dry on the plate. Therefore, it is necessary to reduce the viscosity of the ink appropriately.

　　3. The impact of printing speed: If the speed is too slow, it prolongs the evaporation time of the solvent in the ink, making it easy for the ink to dry and solidify in the mesh. By appropriately increasing the printing speed, the drying speed of the ink can be slowed down.

　　4. Clean the surface of the embossing roller, remove surface dust and ink, and replace damaged embossing rollers.

　　5. Printing material issues: In the case of poor surface tension treatment, the material can be treated with corona discharge or the printing material can be replaced.

　　6. Adjust the angle between the scraper and the plate roller according to the actual situation. The pressure and scraping angle of the scraper are determined by the depth of the printing plate text and the ink application of the printing paper.

　　7. For plate blocks with rich highlights, if there is no improvement after adjusting the scraper pressure and angle, reducing ink, and adding slow drying agents, it may be considered a quality issue with the plate roller, and shallow layers should be raised appropriately.

　　8. For plug plates with medium and dark tones, check whether there are defects in the mesh points and inner walls of the mesh holes, or whether there are burrs on the edges of the chrome plated mesh points, without improvement after adjustment.