Corrosion investigation of fire-gilded bronze involving high surface resolution spectroscopic imaging

•Fire-gilded bronze prepared by ancient methods (Au–Hg layer on Cu–Sn–Zn–Pb–Sb).•Heating during gilding induces Sn and Znenrichment in the top part of the gilded layer.•SR-HRPES mapping of corrosion craters (cross-section) after accelerated ageing.•Selective dissolution of Cu and Zn in the craters induces Sn species enrichment.•The main species in the craters are related to hydroxi-oxide compounds. Gilded bronzes are often affected by severe corrosion, due to defects in the Au layer and Au/Cu alloy galvanic coupling, stimulated by large cathodic area of the gilded layer. Galvanic corrosion, triggered by gilding defects, leads to products growth at the Au/bronze interface, inducing blistering or break-up of the Au layer. In this context, fire-gilded bronze replicas prepared by ancient methods (use of spreadable Au–Hg paste) was specifically characterised by compiling complementary spectroscopic and imaging information before/after accelerated ageing with synthetic rain. Fire-gilded bronze samples were chemically imaged in cross-section at nano-metric scale (