of pulp dry matter egu unit for cellulase activity defined in wo 91 07542 the process of the invention includes bleaching with a reductive bleaching agent which may be hydrosulfites e g sodium or zinc dithionite sodium borohydride or sodium bisulphite for e g sodium dithionite the concentration used in a normal reductive bleaching is typically in the range of 0 05 to 5 0 by weight on dry pulp matter conventional conditions for reductive pulp bleaching may be used typically ph will be in the range 3 7 throughout the reaction other additives commonly used in reductive bleaching may be present such as sodium polyphosphate sodium bicarbonate and complexing agents e g edta dtpa stpp the bleaching temperature is in the range 40 u00b0 90 u00b0 c normally 50 u00b0 70 u00b0 c and the reaction time is in the range 0 5 5 0 hours normally around 3 hours the consistency of the pulp is in the range 2 30 typically 3 8 conventional reductive bleaching is generally followed by a draining off of the bleach liquor and washing of the bleached pulp one bleaching stage may be followed by other stages this can be e g one or more reductive bleaching stages or one or more oxidative bleaching stages using peroxy bleaching agents or combinations of oxidative and reductive bleaching.