understood that brightness values are obtained according to the standard specification established by tappi procedure t 646 os 75 the crude clays were beneficiated according to the general practice used in kaolinite processing industries the beneficiated clays were classified by centrifugation to 94 less than 2 micrometer e s d equivalent spherical diameter the classified clays were flocculated using 0 25 by weight of aluminum sulfate and adjusting the ph to 3 5 with sulfuric acid the flocculated kaolinites were filtered the significantly dried about 20 moisture remains kaolinites were redispersed with 0 25 by weight of sodium polyacrylate and the ph adjusted to about 7 0 the redispersed kaolinite was spray dried being referred to herein as 34 control i 34 this also corresponds to the commercial product betagloss u00ae of the assignee e c c america inc atlanta georgia in many instances one component of the desired bases was added prior to spray drying the moisture content of the spray dried kaolinite was about 1 0 by weight the relative sedimentation volume of treated and starting material was measured to determine the extent and nature of aggregation in the procedure a nearly 55 solids slurry of pigment was prepared that contained 0 3 milliliter of sodium polyacrylate this slurry was then spun at 7000 rpm for 45 minutes the sediment volume was calculated using dry weight of clay wet weight of clay and calculating volume of clay using density of dry clay of 2 6 g ml the spray dried blend control i of fine kaolinite was.