A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 700 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium which is to be removed after completion of grinding. The grinding may be carried out in the absence of grindable inorganic particulate material, wherein the grinding medium is present in an amount of at least about 10% by volume of the aqueous environment, and wherein the microfibrillated cellulose has a fiber steepness of from about 20 to about 50.