Reducing surface roughness of metallic objects and burnishing liquid used

Claim 1

In a process for the physicochemical refinement and burnishing of metal surfaces of objects, in which a mass of elements including a quantity of objects having relatively rough metal surfaces, and a solution capable of reaction with the metal of said surfaces to produce an oxalate or a phosphate conversion coating of softer form thereon, are introduced into a container of a mass finishing unit and are agitated therein for a period of time to produce relative movement among said elements and to maintain said surfaces in a wetted condition with said solution, for conversion of any metal exposed thereon, on a continuous basis, so as to thereby effect a significant reduction in roughness by chemical and mechanical action; and in which said mass of elements is thereafter so agitated in said unit with an aqueous liquid that is at least substantially inert to said metal, to effect removal of said conversion coating and substantial burnishing of the refined surfaces; wherein the improvement comprises said aqueous liquid containing about 0.01 to 1.5 weight percent of a phosphate compound selected from the class consisting of water-soluble tetrapyrophosphate and hexametaphosphate salts, and about 0.002 to 0.2 weight percent of an organic slip agent, said liquid having a pH of about 8.5 to 10.5 and said slip agent being adherent to said metal surfaces at said pH so as to provide lubricity thereto.