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The paper presents the results of experiments obtained using different analytical techniques (optical and electronic
microscopy, infrared spectroscopy, powder X-ray diffraction, X-ray fluorescence, microanalysis) performed on stucco's samples collected in churches and historical buildings in Canton Ticino and Canton Grigioni (Southern Switzerland). The research is principally oriented towards establishing the better analytical sequence for an efficacious characterization of materials and techniques used in making stuccos, in order to satisfy restoration requests. Plastic decorations (stuccoes of 17th and 18th century), imitation marble vertical surfaces - stucco lustro - (19th century) and decorative elements as stucco lustro (17th century) were studied. The experimental data showed the same bottom layer for all the samples; different categories of stucco are distinguishable observing finishing layer characteristics. Petrographic examinations and spectroscopic infrared analyses represent a suitable survey sequence, working on samples of millimetric size (low invasive and high representative criteria for sampling), considering that it is an usual necessity to divide mechanically the different parts of the same material, as for example bottom layer and finishing one, to detect the presence of organic compounds in each layer. More significant results should be obtained employing electron
microscope and microanalysis, using the same thin polished section of optical examinations. Mineralogical and chemical analyses performed by X-ray diffraction and X-ray fluorescence require a greater sample
availability but in this way it is possible to obtain more complete and representative information specifying compounds bound to alteration processes and/or to previous restoration interventions.
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