###### Abstract
It is well known that silver tarnishing usually takes place as a consequence of the reaction between silver and reduced Sulphur-containing compounds such as hydrogen sulphides and carbonyl sulphides present in the air or elemental sulphur. In addition, the prolonged exposure to an environment containing chloride ions--as in coastal areas--or the contact with human skin, could lead to the formation of silver chlorides [1; 6]. Furthermore, past conservation treatments with oils and solvents can be responsible for further degradation processes. [PERSON], in a previous work, stated that excessive oiling in conservation treatments can lead to the darkening and the delamination of painted surfaces. Moreover, the use of impure oils can lead their fatty acids to migrate to the surface [2]. [PERSON] et al. [4] refer about a study on gilt and painted heathers of the XVIII century. The leather and its decorations have been studied through the analysis of cross-sections and by several analytical techniques such as XRF spectroscopy, Raman spectroscopy, and Scanning Electron Microscopy to obtain information about the constitutive materials, the technique, and the preservation state. [PERSON] et al. [7] investigated the painting technique of different gilt leather with special attention to the indigo pigment. In particular, optical microscopy, XRF, SEM-EDX, micro FT-IR, and micro Raman have been used. The analyses identified the pigment in all the works, providing information about the different painting techniques employed. In a previous work [8], we studied a gilt and painted leather coming from an altar frontal and dated to the mid-17 th century. During the conservation treatment at the Istituto Superiore per la Conservazione ed il Restauro, various scientific analyses were employed (optical microscopy, XRF, SEM-EDX, micro-FTIR, and micro-Raman), which allowed the identification of most constitutive materials. More difficult was the identification of the components of gold varnish. In that work, the authors proposed to study the artifact by time-of-flight secondary ion mass spectrometry (ToF-SIMS) to obtain information about the organic substances. Recently, in fact, ToF-SIMS is becoming an increasingly used tool for surface analysis and it is particularly useful for different fields of research to investigate inorganic and organic materials, including cultural heritage studies. Its excellent mass resolution, sensitivity, and high spatial resolution allow obtaining both chemical and distributional (laterally and in-depth) information of a large variety of works of art including gilded metal artifacts [9; 10]. It can be considered a non-destructive technique since it explores only the first atomic layers of the sample. Therefore, the damage induced on the sample under investigation is very limited and further investigations can be performed on the same sample by means of other analytical techniques, by providing complementary information [11; 12]. Moreover, ToF-SIMS has the capability to provide chemical imaging, which allows the identification and localization of the compounds characterizing the sample. Especially, ToF-SIMS spectrometry is particularly indicated for the identification and localization of organic compounds such as resins, oils, binders, dyes, lacquers, etc. difficult to analyze through common analytical techniques largely employed until now [11; 12; 13; 14; 15; 16]. In this work, the chemical characterization of the constitutive materials and of the conservation state of gilt and painted leather by using MA-XRF, ATR-FTIR, and ToF-SIMS were carried out to localize and identify inorganic and organic species. The achieved information on the constitutive materials, manufacturing technique, and degradation products can be very useful in establishing restoration and conservation interventions and to ensure a long and stable chemical-physical life to these precious works of art.