How to Solve Spots in Gravure Printing?
Spots in gravure printing refer to uneven tones where ink appears with varying depths on the substrate, resulting in uneven print impressions. This issue can occur when the solvent drying rate in the ink is too slow, or when the ink is excessively diluted, leading to low viscosity. While the high tones may be satisfactory, spots can emerge in the low tones. If the ink is too thick, especially when it contains a high amount of solid components (pigments, fillers), excessive tackiness can also cause spotting. Uneven paper surfaces or poor wetting of the substrate by the ink can contribute to this problem.
Solution:
Adjust the ink to a slightly thicker consistency; avoid excessive dilution or consider increasing the ink volume appropriately.
Switch to a higher-quality paper with better surface characteristics.
Adjust the ink viscosity accordingly; increase it if necessary.
Use special additives to enhance the ink's wetting properties on the substrate.
Incorporate pigments or fillers with lower oil absorption in the ink to appropriately reduce its rheological properties.
Introduce certain additives to improve the ink's wetting on the substrate.