Aged bronze patina prodn., esp. in antiques restoration - by spray metallising and applying paste of silica in ammoniacal copper sulphate soln.

摘要

An aged appearance is given to bronze coated articles, esp. of ferrous metal, by (a) preparing the surface of the article, spray metallising with a layer of Cu and then a layer of Zn-Al alloy with high Zn content at least on the regions to be bronze coated, (b) applying a layer of bronze with high Cu content, (c) treating the bronze layer with a viscous paste based on copper sulphate, sal-ammoniac and liq. ammonia mixed with silica powder, and (d) removing the paste after drying by careful use of water and brushing. The green patina produced is identical to that of natural patinas and has good corrosion resistance and adherence.