A method of producing a brush for carrying out surface roughing, polishing, lapping, and smoothing operations comprises a first molding operation of one or more mixes including one or more moldable synthetic materials so as to obtain a base portion (6; 160) and a plurality of bristle members (3; 130, 130a, 130b) projecting from a surface (6a; 160a) of the base portion (6; 160) and including at least one abrasive material. The invention also relates to a brush tool of synthetic material including one or more abrasive grain material in the bristle members (3; 130, 130a, 130b) thereof.