alkaline peroxide mechanical pulps sometimes referred to u201c apmp u201d or simply u201c amp u201d may likewise be utilized in accordance with the present invention lignin rich pulps generally have a lignin content of more than 5 based on the weight of the pulp typically more than 10 percent and suitably about 20 percent or more lignin content by weight a phloroglucinol color delta of a pulp refers to a color difference between an absorbent sheet made with the pulp stained with phloroglucinol stain and a like absorbent sheet made from the same pulp which has not been stained this quantity is thus a property of the pulp from which the absorbent sheet is made the phloroglucinol color delta of a pulp may be the difference in l a b or brightness as described hereinafter in these instances the phloroglucinol color delta of the pulp is simply referred to as delta l delta a delta b or delta brightness of the pulp respectively the delta a values versus percent groundwood are illustrated in fig1 for two types of groundwood note also fig3 the relationship between delta a and kappa number is shown in fig5 for refiner mechanical pulp the invention is perhaps better understood by reference to fig6 and 25 it is seen in fig6 that at a given percent groundwood level pulp containing treated mechanical pulp bctmp exhibits much lower delta a values than pulp containing like amounts of untreated groundwood rmp likewise it is seen in fig2 that at a given kappa number tappi method t 236 om 99 that pulps containing bctmp exhibit lower delta a values than pulps with corresponding kappa numbers.