At the end of the Middle Ages, “applied brocade” was one of the most sophisticated ways of imitating prestigious textiles, using pigments, organic materials, and metallic sheets (tin and gilding). This article is dedicated to the study of “applied brocades” observed on 6 religious statues from the Savoy Duchy, where a severe degradation of the metallic parts has been systematically detected. The elucidation of the mechanisms of the metal sheet degradation is crucial for a better understanding of the ancient manufacturing techniques as well as for the selection of the best restorations. This article is based on a multi-analytical approach involving non-invasive and in situ analytical techniques (XRD, XRF), synchrotron imaging on micro-samples (CT-XRD), and analyses on cross-samples (SEM-EDX, and ToF-SIMS). Tin foil analyses show no evidence of metallic tin, but demonstrate the presence of two types of tin alteration products indicative of an atmospheric corrosion: romarchite (SnO) and cassiterite (SnO2). XRD pattern treatments highlight the average crystalline size of both corrosion products: about 10 nm for SnO2 and 50 µm for SnO. Cassiterite is also present in larger proportions than romarchite. The gildings show the presence of both gold and silver. The atmospheric corrosion of silver has been identified as AgCl.