| http://www.w3.org/ns/prov#value | - If an acid, e.g. sulphuric acid, is added after a HAPB to the suspension of pulp and bleaching chemical, so that the bleaching liquor pH is lowered to 12, for example, and the bleaching is allowed to continue for a further 60 minutes before termination according to the method given above, a brightness is obtained which is practically the same as with bleaching for optimum brightness.
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