Calender blackening

1 . Blackening is usually due to streaky or overall excessive sheet moisture.
— sheet is too wet out of last dryers.
— increase dryer temperatures to dry the sheet or slow down machine.
— for streaky calender blackening refer to “Wet Streaks”.
— correct basis weight and moisture profiles.
2. Improve formation.
3. Reduce calendering by reducing the loading pressure or using fewer nips.
— check and adjust calender loading.