An aqueous coating composition for reducing friction and/or blocking at a surface, said composition comprising a solid lubricant and a modified or synthetic clay mineral having thickening properties such that a 2% by weight aqueous dispersion of the modified or synthetic clay mineral thickener has a viscosity of at least 1000 mPa·s. Preferred clay minerals used as thickeners are preferably smectite clays such as saponite, hectorite, stevensite, sauconite, bentonite, beidellite, nontronite, or montmorillonite.