GB491173A - Method of repairing the surfaces of ferrous metal bodies - Google Patents

Abstract

In repairing ferrous metal bodies by securing a coating or filling of metal thereon, e.g. in filling depressions or dents in an automobile body by means of sprayed metal, the ferrous metal surface is cleaned by abrasion, rubbed with a composition comprising an abrasive, hydrochloric acid, mercury bichloride, zinc chloride, copper sulphate, and metallic mercury until a uniform bright coating is obtained, and is then coated or filled by spraying lead or lead alloy thereon, the final coating &c. being sanded down flush with the surface of the article and then painted if desired. The preliminary coating composition may be made up in two parts, one containing the metallic mercury, the mercury bichloride, and the abrasive, which may be a mixture of quartz sand and the abrasive known under the Registered Trade Mark "Crystolon," and the other being an aqueous solution of the other components. The two parts may be mixed immediately before application or the aqueous solution may be applied first. The composition is preferably applied with a wooden paddle and rubbed in with a felt pad. A copper coating forms on the ferrous surface which then combines with the mercury to form an amalgamated coating which also includes zinc deposited from the zinc chloride. The spraying of the lead or lead alloy is preferably effected by the spray gun described in Specification 491,172, [Group XXIX], the nozzle being moved with a circular motion first around the outer edge and then towards the centre of the area to be coated, until the metal has been built up above the level of the surface of the work. The coating is then sanded down to the desired level. If respraying is necessary, e.g. if after sanding insufficient metal is found to be present, the surface is rubbed again with the preliminary coating composition several times and with considerable pressure and the coated surface immediately resprayed.