Dosed in grams per ton at the wet end or size press, shading dyes absorb a little yellow, orange and red light, so the reflected light leans blue and the sheet looks whiter, even though brightness drops slightly. They work alongside optical brighteners to set the final shade and keep tint near neutral. The trade-off is fixed: every bit of dye that raises whiteness also lowers R457.
Shading dye is up 20 percent and brightness is down half a point, that's the price of hitting whiteness.
Also heard as
- hueing dye
- toning dye
Related terms
Bluing
Mill talk for adding blue or violet dye to make a white sheet look whiter by masking its yellow cast.
Tint
Companion value to CIE whiteness that tells whether a white leans toward green or toward red.
Whiteness
How white a surface looks to the eye, judged across the whole visible spectrum rather than one blue band.
Shade
The exact color of a paper grade measured against its approved standard, for whites as well as tinted sheets.
OBA
Optical brightening agent: a dye that absorbs UV light and re-emits it as blue, making paper look whiter.