The word comes from laundry bluing, the blue added to a rinse to whiten cloth, and papermakers use it the same way: a trace of blue or violet dye pushes b* negative and hides yellowness from lignin or recycled fiber. It raises perceived whiteness but always lowers brightness, so it cannot rescue a brightness spec. Heavy bluing makes a sheet look grayish in daylight.
Pulp came in yellow again, so we're leaning on bluing to keep the sheet looking white.
Also heard as
- blueing
Do not mix it up with
- OBA: OBA adds blue light by fluorescence and raises brightness; bluing removes yellow light by absorption and lowers it.
Related terms
Shading dye
Small dose of blue or violet dye used to cancel the yellow cast of a white sheet and steer its tint.
b*
Yellow-blue coordinate in CIELAB, positive toward yellow and negative toward blue, watched closely on white papers.
Whiteness
How white a surface looks to the eye, judged across the whole visible spectrum rather than one blue band.
Brightness
The blue-light reflectance of pulp or paper, read at an effective wavelength of 457 nm and reported as a percentage.