An excessive increase in the size of a halftone dot from film to the printed image.
Causes:
-Excessive ink volume;
-Excessive plate thickness or plate swelling;
-Wrong tape or trapped air;
-Excessive pressure settings;
-Poor ink metering application;
-Damaged or worn press parts;
-Dirt on impression and/or plate cylinders;
-Viscosity too low.
Solutions:
- Reduce anilox volume to a minimum while maintaining colour balance;
- Use thinner plates;
- Check for trapped solvents in the finished plate;
- Change to a cushion mounting tape;
- Check for bubbles under the mounting tape, burst and remount plate;
- Reduce pressure settings to a minimum;
- Use a doctor blade metering system;
- Check and replace damaged or worn gears, bearings or cylinders;
- Clean impression and/or plate cylinders;
-Check and maintain ink viscosity.
