Relation between CIE lab color values and the lignin content of kraft pulps during bleaching

Abstract

Residual lignin in unbleached kraft pulp and unbleached pulps from CEHDED stages correlate well with the color values of the same materials of known CIE L*. a*, b*, C* and h* values. L* and C* values of pulps were evaluated to estimate their residual lignin. By using L* and C* values. an equation enabling an on line-control of the bleaching parameters could be established.