An aqueous suspension comprising an inorganic particulate material and dimethylethanolamine, use of dimethylethanolamine to prevent pH decrease or reduce the rate of pH decrease of an aqueous suspension comprising an inorganic particulate material over time, use of dimethylethanolamine as an anti-microbial additive in an aqueous suspension comprising an inorganic particulate material, and a method of preparing an aqueous suspension comprising inorganic particulate material.