In particular, the average values of the fiber width
insignificantly decreased after Pa-E stage and maintained
unchanged during further bleaching. The changes of fiber
coarseness i.e. weight of fiber per fiber length unit were
also insufficient. Probably, this is related to the fact that
hardwood pulp fibers are narrow with small number of
pores therefore there were no significant swelling of fibers
observed. Coarseness of fibers slightly reduced only at
acid stages of pulp treatment.