Grinding pretreated hardwoods : experiments on quaking aspen, sweetgum, red alder, black tupelo, sugar maple, red oak, and cottonwood

Mild treatments with neutral sulfite solutions before grinding increased the freeness and the long fiber fraction of several hardwood groundwood pulps.Strength, brightness, and density were only slightly affected.Increasing the severity of the pretreatment increased the strength and density of the pulp and decreased the brightness and the opacity of the papers in which it was used.Chemigroundwood pulps were made that approached neutral sulfite semichemical pulps in strength and could probably be used for about the same purposes.The darker chemigroundwood pulps were easily brightened with a singlestage hypochlorite treatment.The experiments indicate that it may be possible to substitute hardwood chemigroundwood pulps entirely, or in part, for softwood groundwood in newsprint, book, and toweling papers and also to substitute mixtures of hardwood groundwood and hardwood chemigroundwood for softwood groundwood.