Brightness

1. Check the brightness of the furnish components.
— raw stock, broke, fillers.
2. Check the fresh water quality.
— varying color, turbidity, anionic trash, etc. cause problems.
3. Increase usage of high brightness fillers.
4. Check and adjust dye levels.
— too much dye (any color) lowers brightness.
— a slight bluish tint appears whiter (less yellow).
5. Check the wire pit and size press pH.
— pH affects additive and dye retention thus influencing shade.
6. Check the mill procedure for the addition of optical brighteners
7. Check and adjust refining if other tests permit.
— higher density sheets are darker.
— refining affects additive and dye retention.
8. Check retention aid.
— good first-pass retention is critical for color control and for effectiveness of brightening additives (clays, TiO2).
See related topic, Filler content varying.