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The degradation process involving the formation of metal soaps in drying oils is a well-known problem due to cations from pigments reacting with free fatty acids from the oil. The aggregation of these carboxylates in semi-crystalline structures can lead to eruptions through the paint layers and ‘blooming’ on the surface. In this work, the metal soaps formation in presence of natural resins has been assessed and studied by means of Fourier transform infrared spectroscopy with experiments concerning the ageing of drying oil and different natural resins (shellac, dammar and colophony) in the presence of common historic pigments (smalt, ochre, umber, azurite, lead white, zinc white and titanium white). Mixtures of resins and pigments have been exposed to photo-ageing in solar box up to 1000 h, thermal ageing at 50 °C up to 1100 h and 6 month of room conditions exposure as reference. The decrease in the intensity of the carbonyl band in the spectra, as well as the contemporary increase of the metal carboxylates (in the range from 1500 to 1650 cm −1 ) absorption bands, were used as the main indicators of metal soap formation. It has been observed that some pigments, particularly zinc white and smalt, present a ‘catalytic’ effect favouring the simultaneous formation of associated oxalates. The formation of oxalates and different degradation products from natural resins in the presence of pigments is particularly important, as it deeply affects the removability of varnishes and, more generally, the cleaning processes. Moreover, it permanently modifies the interface between painting and varnish layers as well as the aesthetic aspects of the painted surfaces. The influence of natural resins reactivity with pigments and their role in the oxalate formation is an issue still unexplored. [ABSTRACT FROM AUTHOR]

The study of polished cross sections is a well-assessed and practical method to investigate the stratigraphy of paintings and multilayer polychromies on works of art, in general. Analyses on cross sections allow us to characterize, at once, all the layers in the stratigraphy, giving information about the artists technique, the number of layers and their composition and sometimes about the conservation history of the artefact. In this paper, the application of an imaging detector focal plane array (FPA) coupled to an infrared (IR) microscope has been studied, focusing on the characteristics and potential of the different working methodologies (attenuated total reflectance (ATR) and total reflection). FPA detector coupled with ATR crystal can 'localize' IR information coming from a 30 × 30μm sample area, in a 64 × 64 dot matrix detector. In particular, an innovative analysis methodology has been tested for the total reflectance measurements in order to obtain maximum information with single measurements. Micro-infrared total reflection measurements have been carried out in an extended IR range (from 1,000 to 5,266 cm) exploiting the broad spectral response of mercury cadmium telluride detector in order to include overtones and combination bands from near-infrared spectral range without any modification of the standard mid-infrared micro-FT instrumentation. The potentialities of this new approach have been successfully transferred in the imaging/mapping investigations with a minimal tuning of the apparatus. Results obtained on a polished cross section coming from a modern painting and on a micro-sample of a wood polychromy from an undated historic polyptic are shown for demonstration. [ABSTRACT FROM AUTHOR]

The painting materials used by Lucio Fontana were investigated through the analysis of 28 Spatial Concept works created between the early 1950s and the artists death in 1968. The pictorial media were analyzed by means of numerous techniques including Fourier transform infrared spectroscopy, pyrolysis-gas chromatography-mass spectrometry, scanning electron microscopy, and X-ray fluorescence. This study has provided a more complete understanding of the artist's technique, as it was found that Lucio Fontana had already begun experimenting with new synthetic pictorial and binding media such as alkyds and polyvinyl acetates at the beginning of the 1950s, and polyesters during the early 1960s. Although he never abandoned the use of commercial oil paints, Fontana's application of these new materials continued in an infinitely varied search for innovative expressive effects. The characterization results explain the physical and mechanical properties of the paint layers, and may be correlated with the conservation state of the works analyzed. All the results have been compiled and are discussed together with the artist's practices and their evolution over time. [ABSTRACT FROM AUTHOR]