In the reported investigation, three-, four-, five-, and six-stage sequences for the production of both semibleached and fully bleached kraft pulp from mixed New Zealand beech species (Nothofagus spp. ) were evaluated simultaneously by using a statistically designed experiment. Multiple regression techniques were used to develop equations expressing brightness as a function of the experimental variables. The specific bleach sequences evaluated and the brightness ranges over which they were found to be effective included: CEH and/or D//cEH, 55-80%; CEHD and/or D//cEHD, 78-88%, CEDED and/or D//cEDED, 88-90%; D//cEHDED, 88-92%. Sequential chlorination (D//c) reduced NaOH consumption in the first extraction stage, and increased the initial and aged brightness of both the semibleached and fully bleached pulps. Hydrochlorite addition level was the primary factor influencing H and D//1 stage brightness as well as pulp viscosity.
