Calender spots

1. Check screening facilities and method of chemical make-up for wet-end additives.
— either may cause shiners or fisheyes in sheet (defoamer, retention agent, etc.).
2. Improve sheet formation to eliminate stock lumps.
3. Check temperature and concentration of the size press solution.
— check batches for proper preparation.
4. Check size press filters.
— clean, and make sure filter by-pass valves are closed to avoid contaminating system.
5. Reduce moisture of sheet entering size press (excessive starch pick-up).
6. Eliminate size press solution splashing on carrier ropes at size press.
7. Increase temperature in dryer section after size press to prevent the surface sizing from building up on calender rolls.
8. Clean rolls and adjust doctors to remove pieces of paper sticking to calender rolls.

9. Clean rolls and close windows or put up protective shields to prevent dirt from blowing in on stack.
See also Calender roll cleaning and Calender scabs