Characterization of black pigment used in 30 BC fresco wall paint using instrumental methods and chemometry

Abstract

Background and methodsSeveral standard powdered black pigments were characterized by means of thermogravimetry TG-DTG and allied techniques. These pigments were used to make standard plaster frescoes at this purpose prepared. The latter ones were subjected to Raman and reflectance analysis. The results obtained, together with TG data, were chemometrically processed and used to identify an analogous standard fresco fabricated by an unknown commercial black pigment, obtaining excellent results.ResultsThe same colorimetric and reflectometric techniques, coupled with suitable chemometric techniques, were then successfully used to identify the type of black pigment present in an ancient roman fresco of the Imperial Age (30 B.C.).ConclusionTG-DTG resulted useful techniques to autenticate powdered black pigments.Colorimetry and Raman, but also the only colorimetry, were useful to identify an ancient black pigment in situ.

Raman microspectroscopic analysis of decorative pigments from the Roman villa of El Ruedo (Almedinilla, Spain)

“…1590 and 1330 cm À1 , respectively, which indicates the presence of carbon. These wavenumbers depart slightly from previously reported values for Roman carbon pigments [17,20,25,26]; the differences, however, can be ascribed to differences in the conditions where the carbon material was obtained (particularly pressure and temperature, which have a decisive influence on crystallinity). Alternatively, the wavenumber differences may have arisen from experimental differences in recording the spectra; thus, the laser focal point can reach completely different temperatures during measurements, but the exact influence of variations has not yet been established.…”

The Bone Black Pigment Identification by Noninvasive, In Situ Infrared Reflection Spectroscopy

“…Several studies have been devoted to the molecular characterization of carbon-based black pigments by means of different destructive and microdestructive techniques such as Raman, SEM-EDX, XRD, ICP-AES, and FTIR [ 3 – 7 ]. Generally, the diagnostic difficulties which lie in the characterization of this pigment are due to the various origins and/or manufacturing processes related to (i) characterization of carbonaceous phase [ 8 ] and (ii) identification of noncarbon constituents. Regarding this last point, the most obvious example of noncarbon constituents is the inorganic materials in animal bone pigments.…”

Suitable classification of mortars from ancient Roman and Renaissance frescoes using thermal analysis and chemometrics

“…On the other hand, recently we showed how thermal analysis, in particular thermogravimetry (TG-DTG), coupled with chemometric methods, can be a valid tool for the characterization and classification of several types of archaeological finds and cultural heritage, e.g. pigments [ 15 ], marbles [ 16 ], pottery [ 17 ], fossil bones [ 18 ], and so on. Therefore, we decided to apply thermogravimetric analysis also to several mortars sampled from different ancient Roman and Renaissance frescoes to determine whether, also in the case of ancient mortars, the simple combination of thermal analysis and chemometric methods could be used to obtain a fast but correct classification of ancient mortar samples of different ages.…”