a method of smolder protection of mattresses and upholstery materials selected from the group consisting of cellulosic (cotton) materials and flexible polyurethane foam covered with a smolder-prone fabric which comprises coating or impregnating at least a layer of said material with an application of sulphur in at least 25 g/sq m sulphur may be coated or impregnated utilizing any of the ordinary forms of elemental sulphur. in thick treated layers, smolder inhibition is best achieved by penetration of the sulphur to a depth of 3 mm or greater. sulphur may be applied by liquid or vapor treatment, or as a solid with later melting, or from solution. the present invention in its broader aspects contemplates the addition of sulphur to cellulosics, such as rayon, cotton batting, wood fibers, etc., as well as to such materials as flexible polyurethane foam, neoprene rubber, and latex for the smolder protection of the materials treated without an overlay of a smolder-prone fabric