Abstract: Disclosed for use in treating a metal, e.g., an alloy of silver as aforesaid, is a water-based composition comprising a treatment agent selected from an alkanethiol, alkyl thioglycollate, dialkyl sulfide or dialkyl disulfide and at least one of an amphoteric, nonionic or cationic surfactant in a concentration that is effective to solubilise the treatment agent. Preferably the composition comprises at least a non-ionic relatively hydrophobic surfactant e.g. cocamide DEA. The composition is particularly suitable for the treatment of Ag—Cu—Ge alloys.

Abstract: An alkanethiol, alkyl thioglycollate, dialkyl sulfide or dialkyl disulfide may be used to surface treat of an alloy of silver containing an amount of germanium that is effective to reduce firestain and/or tarnishing. The treatment has been found to further reduce tarnishing of the alloy such that a sample can be supported close above a 20% solution of ammonium polysulphide for at least 30 minutes while retaining a generally untarnished appearance. The treatment may be carried out at the end of manufacturing a shaped article to give rise to an article that will preserve its untarnished appearance both during transit to a point of sale but during subsequent display for an extended period.