size and alkali performance in the bleaching of ccs cold caustic soda wood pulp four grades of mgo were trialled each one identified by its particle size distribution each sample of mgo had approximately the same surface area particle size and surface area for each of the samples is given in table 1 ccs chemi mechanical pulp pretreated with dtpa to remove metal ions was retrieved from the washers in the bleach plant at the boyer mill an equivalent mass of 20 grams od of pulp was weighed out and placed in a plastic breaker dtpa was then added as 0 15 v w on the pulp and mixed mgo as 0 4 wow enough water to give a stock consistency of 12 and peroxide as 1 6 v w on pulp was added and mixed for 2 minutes the pulp was wrapped in plastic bags and placed into a constant temperature water bath at 65 u00b0 c a 3 gram od sample was removed from the bath at intervals of 2 3 and 4 hours this was then made into a brightness hand sheet using the standard boyer pulp mill method these were dried overnight in a constant temperature humidity room and tested for iso brightness this procedure was repeated.