INK DRYING TOO QUICKLY


Ink dried on plates and rollers and not transferring to substrate, normally found on leading edge of substrate.

 

Causes: 

- Low pH due to loss of amine;

- Uncontrolled viscosity;

- Air spillage onto printing unit;

- Incorrect solvent balance;

- Insufficient transfer;

- Web temperature too high when entering print station;

- High temperature and/or low humidity in pressroom.

 

Solutions:

- Add pH stabiliser solution;

- Maintain correct printing viscosity. Do not print at high viscosity;

- Keep forced air away from units. Air movement near doors, windows and fans is to be avoided. Check interdeck dryers for overflow;

- Use correct solvent mixture, weak solvents will precipitate ink components;

- Use correct anilox. Do not use very low viscosity;

- Reduce preheat web temperature entering print station;

- Control pressroom environment to optimum conditions.