Spoken as b-star, it is the CIELAB coordinate that captures most of what makes a white look warm or cool. Unbleached and recycled fiber pushes it positive, while optical brighteners and blue or violet shading dyes drive it negative. On white grades it is often the tightest tolerance in the shade spec, because the eye catches a small yellow shift sooner than a change in lightness.
b-star moved half a unit yellow after the pulp swing, so give the blue dye another tenth.
Also heard as
- b-star
- b value
Related terms
CIELAB
Color space describing a color by lightness L* plus a* for red-green and b* for yellow-blue.
Yellowness index
Single number that rises as a near-white sample shifts toward yellow, used to track aging and lignin effects.
Shading dye
Small dose of blue or violet dye used to cancel the yellow cast of a white sheet and steer its tint.
Delta E
Single number for the total color difference between a sample and its target, usually in CIELAB units.