Studies on paint cross sections of a glass painting by using FT‐IR and Raman microspectroscopy supported by univariate and hierarchical cluster analyses

Abstract

Fourier transform infrared (FT‐IR) and Raman spectroscopy is used for the non‐destructive analysis of painting materials and ageing compounds in micrometric cross sections of a glass painting. The combination of both techniques in conjunction with imaging/mapping function provides the spatial distribution of chemical components identified in vibrational spectra. The aim of our work is to show the applicability of the FT‐Raman mapping technique in the detection of painting materials. We also compare Raman information gained by using two laser excitations at 532 and 1064 nm implemented in microspectrometers with different confocality and spatial resolution. In turn among FT‐IR imaging techniques, we compare chemical images recorded in external reflection and attenuated total reflection modes that give chemical images of different size and spatial resolution. Our FT‐IR and Raman imaging characterize a number of painting materials such as pigments, binders, fillers as well as degradation products. Raman maps are constructed by using the univariate analysis. In turn, a profile of IR images requires the use of a more complex methodology. Here, we compare FT‐IR images of the painting cross sections obtained by using the univariate and hierarchical cluster analysis. We clearly show that the multivariate approach is a powerful tool for the credible construction of IR images, providing the relevant chemical information on the multicomponent stratigraphy of the samples. Moreover, the combination of all the methods allows us to demonstrate their degree of utility for the study on the paint cross sections of the works of art. Copyright © 2013 John Wiley & Sons, Ltd.

Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials

“…This approach in processing IR and Raman images was introduced by us. 18 Vis-Raman spectra were collected by using a Raman microspectrometer WITec Alpha 300, equipped with an air cooled solid state laser operating at 532 nm and a CCD detector. A microscope was coupled with a laser and a spectrograph via a single mode optical fiber with a diameter of 50 µm.…”

Raman Spectroscopy of cultural heritage Materials: Overview of Applications and New Frontiers in Instrumentation, Sampling Modalities, and Data Processing

“…Raman mapping using a conventional motorised stage is used in the cultural heritage field on micro-samples and cross-sections of samples such as paint layers (in favourable cases where fluorescence is not a complete impediment to analysis) [94,153,287], calcium oxalates layers deposited on the surfaces of monuments as deterioration products or as intentional mineral consolidation treatments [92,93], iron corrosion layers [210], and other corrosion products of archaeological metal objects [18] or porcelain cards [116]. When it comes to in situ analyses, unless the object fits under the microscope and can be securely held on the motorised stage, which is not often the case, different approaches must be considered.…”

“…By far though, the most highly used approaches rely on PCA, HCA and PLS-DA for materials classification in many contexts: to identify and discriminate pigments [214,223,287,297], dyes [121] and inks [238]; to characterise organic media [105,[215][216][217]229] and metallic soaps [226]; and in the related domains of forensic science [123] for the analysis of industrial paints [212]. In essence, data reduction processes using PCA for the automatic identification of pigments in works of art work by first performing data pre-treatment of a reference spectral library, including spectral range selection, baseline subtraction, linear interpolation, and intensity normalisation.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part VIII

“…The combination of these methods demonstrates their utility for the study on the paint cross sections of the works of art. [189] Tomasini and coworkers identified atacamite as a natural pigment in a South American colonial polychrome sculpture from the late XVI century. They found that atacamite was used as the green pigment and identified it for the first time as a mineral pigment in a colonial sculpture made in the Viceroyalty of Peru.…”

“…Staniszewska et a l. studied paint cross sections of a glass painting by using FT‐IR and Raman microspectroscopy supported by univariate and hierarchical cluster analyses. The combination of these methods demonstrates their utility for the study on the paint cross sections of the works of art . Tomasini and coworkers identified atacamite as a natural pigment in a South American colonial polychrome sculpture from the late XVI century.…”