(57) A method of increasing the coefficient of static friction of a cellulosic sheet which method comprises the steps of preparing a sprayable aqueous coating composition comprising an aqueous suspension of a finely divided particulate inorganic material comprising material selected from the group consisting of kaolin clay, calcined kaolin, ground natural calcium carbonate, chemically precipitated calcium carbonate and zeolites, and, preferably from 4% to 60% by weight, based on the dry weight of the particulate inorganic material, of an adhesive, and spraying the coating composition on to the surface of a cellulosic sheet, in a quantity sufficient to give, after drying of the coating, a suitable coat weight per unit surface area, eg in the range of from 0.5g.m^-2 to 3.0g.m^-2. The static coefficient of friction of the coated sheet may be at least 0.5.