Fourier transform Raman spectroscopic study of pigments present in decorative wallpapers of the middle nineteenth century from the Santa Isabel factory (Vitoria, Basque Country, Spain)

Abstract

One of the earliest wallpapers manufactured by the Santa Isabel factory (Vitoria, Basque Country, Spain) (1845) was found at the Torre de los Varona (near Vitoria) during restoration work on the building. As part of this cleaning and restoration work, the identification of the wallpaper's pigments was carried out by Fourier transform (FT) Raman spectroscopy. Fragments of paper were set in a sampler kit for planar surfaces. By moving the paper samples, it is possible to locate the laser beam's spot at the point that it is going to be analysed with a spatial resolution of about 0.5 mm. With this method it is possible to map a surface of several square centimetres without the need for an optical microscope. As FT-Raman analysis is totally non-destructive, the samples were restored and integrated with the whole wallpaper at the end of the analysis. Small particles of pigment were collected for the analysis of the pink and green colours by atomic absorption spectrometry (AAS). In both cases, the damage caused by the pigment sampling was minimal and non-visible. BaSO 4 , CaCO 3 , Pb 3 O 4 , PbCrO 4 , PbO, Prussian Blue, gypsum and an organic black pigment were detected. It is important to take into account the laser beam's penetrative power in order to interpret the spectra correctly. The identification of only eight pigments to make 12 different colours, mostly in two different shades, shows the ability of the wallpaper manufacturer to create a rich palette at low cost. This type of primitive industrial decorative work has become real artwork that it is necessary to preserve and restore.

Application of confocal Raman spectroscopy to thin polymer layers on highly scattering substrates: a case study of synthetic adhesives on historic textiles

“…Specific examples include pigments in fine art, 7 wall paintings, 8 wall coverings, 9 polychromes, 10 icons, 11 papyri and manuscripts 12 -19 and pottery. 20,21 We have recently developed a protocol for applying Raman spectroscopy to the identification of pigments on historic painted textiles, in order to aid conservation of these culturally important artifacts.…”

Peer Reviewed: FTIR Spectra Database of Inorganic Art Materials

“…Only one of the four samples, sample 3 (Figure 2c), corresponds to pure lead white (2PbCO 3 ·Pb(OH) 2 ), whereas sample 2 ( Figure 2b) is lead white mixed with PbSO 4 , and sample 1 (Figure 2a) is actually PbCO 3 . The most surprising case is sample 4 (Figure 2d), which is PbSO 4 .…”

“…1800, could be used instead of artificial ultramarine blue. Its chemical composition supposedly corresponds to a mixture of CoO·Al 2 O 3 and H 3 PO 4 .…”

“…As can be seen from the results in Figure 5, both whites are different. The background white was BaSO 4 , and the white in the drawing was CaCO 3 . This is a very interesting finding because CaCO 3 is used by itself as a pigment in this artwork.…”

On the use of photobleaching to reduce fluorescence background in Raman spectroscopy to improve the reliability of pigment identification on painted textiles

“…Raman microspectroscopy has long enjoyed a reputation as the technique of choice for the non-destructive analysis of pigments on a wide range of historic and archaeological artefacts including the analysis of pigments on manuscripts, 1 -15 polychromes, 16,17 icons, 18 Roman intaglios, 19 wall paintings, murals and frescoes, 20 -31 wall coverings, 32,33 postage stamps, 34 funerary artefacts, 35 and fine art. 36 -38 We have already reported its use in pigment identification on painted textiles; 39 however, these artefacts often give spectra in which the characteristic peaks are masked by a large fluorescent background, preventing unambiguous identification of pigments in some cases.…”