Treatment of metal surfaces in the - manufacture of watches

摘要

Metal surfaces used in the manufacture of watches and clocks are provided with a coloured protective coating of metal by treating the coating with a chemical which changes its colour. The colour provided lies between green and violet in the sun spectrum. Pref. a layer of a Ni:Co alloy is coated onto the brass part and this layer is treated with an oxidising agent to form an intensely blue Ni-Co. cpd.