In the printing process, uneven ink color is a common issue that often stems from an imbalance between ink and water control. This can happen when the water level is too high or too low, or when the ink distribution before printing is inconsistent. Here's how to address this problem effectively:
To prevent uneven ink color, it's essential to manage the amount of water used during printing. A key principle is "more ink, more water; less ink, less water." Avoid adding excessive water, as this can cause the ink to emulsify, leading to ink transfer issues and blank spots on the print. The design of the printing plate, including the size and density of graphics, as well as the printing speed, all influence how much water should be used. For example, when the graphic area is large and densely packed, and the printing speed is slow, you may need to increase the water supply. Conversely, if the graphics are small or sparse, reduce the water accordingly.
If there’s too much water, the printed material might feel damp, and water marks could appear on the cylinder. To fix this, you can use extra overprinted sheets to absorb excess moisture, wrap the water roller with white paper to contain the water, or adjust the water delivery speed. After removing the excess water, wipe down the roller to ensure it’s clean and ready for the next run. If these steps don’t work, consider removing the water roller and cleaning it manually.
From the perspective of the printing plate, if the surface appears dull and the print looks full, it’s a sign that the water level is just right. When the water is properly balanced, and the ink is abundant, you can "wrap" the ink around the larger areas of the plate. For smaller areas, add ink carefully, making sure it’s spread evenly across the surface. During the inking process, metal packaging should be monitored closely, and the top wire under the ink fountain should be adjusted promptly to control ink flow locally. Additionally, adjusting the angle of the ink fountain and the ink fountain roller helps maintain consistent ink supply throughout the entire printing process.
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