Indagini preliminari ToF-SIMS su manufatti lignei provenienti dal museo diocesano di Palermo

Abstract

The Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a methodology only recently applied to the study of the artworks. This tecnique allow the acquisition of a high amount of morphological and chemical information, directly related to the surface properties of the investigated sample. Through this technique it is possible to carry out an elemental analysis of the material as well as a determination of molecular ions (organic and/or inorganic) with a molecular weight ≤ 5000 Dalton (atomic mass unit). Moreover it is possible to use this spectrometry in an Imaging mode, that supplies a spatial distribution of the present substances, by the generation of "a chemical image", with a very high resolution. In addition, this instrument allows for the analysis at various depths, permitting the estimation of the chemical composition along a cross section of the sample. In the study of art objects, it is possible to estimate the structural and chemical homogeneity and to study the effects of natural degradation processes, microbiological attack and restoration actions. In the case of a restoration, the analysis is able to identify the type of the employed materials, its degree of penetration in the artwork and chemical modification overtime. A further advantage of this technique is the capability of analyzing very small fragments, with dimensions below a millimetre. In the present work preliminary ToF-SIMS surveying have been carried out, both by spectroscopy and imaging, on some samples from painted wood artwork of the Diocesan Museum of Palermo, that have recently undergone restoration processes. Chemical images made it possible to characterize several materials used by the original artists, the composition of both the preparatory and the paint layers and of the gildings, that in one case resulted to be made with "false gold".