When analytical chemistry is called to support a conservation work on a polychrome surface, one of the main issues is the characterization of the palette. When sampling is permitted a laboratory analytical plan is designed. Since some years, the concerns about the correct conservation of the artworks, advised to avoid sampling; consequently the analytical protocols have been integrated with portable techniques. In fact XRF, FORS, Raman constitutes a valid support in individuating the used pigments. These latter have been recently flanked by portable FTIR; in case of the use of FTIR, spectra have been acquired with a non destructive and non invasive sampling method, via the external reflectance technique. Unfortunately bibliography which can provide reference reflectance spectra is lacking. In this paper a first attempt to build a set of reference data of a painting materials is presented. The FT-IR Spectrometer (Alpha-R, Bruker Optik GmbH) has been used sampling a circular area with about 6 mm of diameter and with the following parameters: 7500-375cm-1 spectral range, 4cm-1 spectral resolution, 200 number of scans. More than 50 pigments, provided by Kremer Pigmente GmbH, as pure pigments, were analysed representing a complete palette. Pulverized pigments were deposited in the cavity of an aluminium sample holder for X Ray Diffraction and the spectra were acquired without the need of further pre-treatment of samples. Moreover nearly 20 different organic substances were applied over a glass slide covered with an aluminium foil in order to acquire binder references. A selection of the spectral reflection features are presented in the paper, together with a discussion and the attribution of the more interesting ones. For each of the pigments part of the study, the characterisation has been completed with a micro-Raman spectrum (Senterra, Bruker Optik GmbH; 785 nm and 532 nm laser lines) and an XRD (X Ray Diffraction) analysis (Panalytical X'Pert PRO) in order to better complete and attribute the spectral data coming from portable FTIR.
Studying pigments via portable FTIR
RAMPAZZI, LAURA;Corti, Cristina;
2015-01-01
Abstract
When analytical chemistry is called to support a conservation work on a polychrome surface, one of the main issues is the characterization of the palette. When sampling is permitted a laboratory analytical plan is designed. Since some years, the concerns about the correct conservation of the artworks, advised to avoid sampling; consequently the analytical protocols have been integrated with portable techniques. In fact XRF, FORS, Raman constitutes a valid support in individuating the used pigments. These latter have been recently flanked by portable FTIR; in case of the use of FTIR, spectra have been acquired with a non destructive and non invasive sampling method, via the external reflectance technique. Unfortunately bibliography which can provide reference reflectance spectra is lacking. In this paper a first attempt to build a set of reference data of a painting materials is presented. The FT-IR Spectrometer (Alpha-R, Bruker Optik GmbH) has been used sampling a circular area with about 6 mm of diameter and with the following parameters: 7500-375cm-1 spectral range, 4cm-1 spectral resolution, 200 number of scans. More than 50 pigments, provided by Kremer Pigmente GmbH, as pure pigments, were analysed representing a complete palette. Pulverized pigments were deposited in the cavity of an aluminium sample holder for X Ray Diffraction and the spectra were acquired without the need of further pre-treatment of samples. Moreover nearly 20 different organic substances were applied over a glass slide covered with an aluminium foil in order to acquire binder references. A selection of the spectral reflection features are presented in the paper, together with a discussion and the attribution of the more interesting ones. For each of the pigments part of the study, the characterisation has been completed with a micro-Raman spectrum (Senterra, Bruker Optik GmbH; 785 nm and 532 nm laser lines) and an XRD (X Ray Diffraction) analysis (Panalytical X'Pert PRO) in order to better complete and attribute the spectral data coming from portable FTIR.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
