Editing Kraft process (section)

===Bleaching===
{{Main|Bleaching of wood pulp}}

In a modern mill, brownstock (cellulose fibers containing approximately 5% residual lignin) produced by the pulping is first washed to remove some of the dissolved organic material and then further delignified by a variety of [[bleaching of wood pulp|bleaching]] stages.<ref>{{cite web|url=http://www.environmentaldefense.org/pdf.cfm?ContentID=1626&FileName=WP5.pdf|title=Environmental Comparison of Bleached Kraft Pulp ManufacturingTechnologies|access-date=2007-09-28|url-status=dead|archive-url=https://web.archive.org/web/20041218171736/http://www.environmentaldefense.org/pdf.cfm?ContentID=1626&FileName=WP5.pdf|archive-date=2004-12-18}}</ref>

In the case of a plant designed to produce pulp to make brown sack paper or linerboard for boxes and packaging, the pulp does not always need to be bleached to a high brightness. Bleaching decreases the mass of pulp produced by about 5%, decreases the strength of the fibers and adds to the cost of manufacture.