Micro‐Raman and particle‐induced X‐ray emission spectroscopy for the study of pigments and degradation products present in 17th century coloured maps

Abstract

Three different maps of the 17th century, two of them of Portugal and the third of the Iberian Peninsula, all of them hand coloured and of Dutch manufacture (copper engraving), were studied in this work. The study was carried out by using particle-induced X-ray emission (PIXE) and micro-Raman spectroscopy. These are two non-destructive techniques that provide complementary information on the composition of the materials: PIXE giving elemental information and Raman providing information at a molecular level. By means of the two techniques it has been possible to identify the inorganic pigments used in the three maps, as well as some products of degradation whose causes are not completely understood yet. This article contributes to a better knowledge of the techniques and palettes used for the colouring of maps of this period as well as the degradations of the pigments. Particular attention is given to the presence of a copper oxalate found in two different maps, its presence being associated with green coloured areas and indicating a degradation of a copper-based green pigment.

Raman spectroscopic study of the degradation of a middle age mural painting: the role of agricultural activities

“…In addition to the techniques described previously, which are well suited to the study of cultural heritage because of their nonsample consuming feature, literature shows the frequent use of additional microdestructive techniques such as particle‐induced X‐ray emission and laser‐induced breakdown spectroscopy . It is important to say that in some cases, important information can be obtained only through destructive analysis.…”

Micro‐Raman spectroscopic analysis of inks and pigments in illuminated medieval old‐Slavonic manuscripts

“…The surface of the green area was crystalline as opposed to the Benche book where it was with flat shine without crystals. Although visually there were differences in the green pigments of the two books, Raman spectra as well as data from SEM–EDX analysis were very similar suggesting some type of verdigris, as in the case of Benche book …”

“…Closer inspection of the spectra suggested the presence of some type of verdigris (organo‐copper complex) with bands at 202, 955, 1070, 1305, 1361, 1445, 1570, 2856–2937‐cm −1 (Fig. (d)) . It has been shown in literature that, depending on the conditions of manufacture, different green organo‐copper complexes could be obtained, which make its identification complicated and uncertain.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part III

“…Another pigment analysis, however, from art works of the 16th to 18th century was performed by Burgio et al [65] These authors studied the non-figurative illumination in five Islamic religious manuscripts held in the National Art Library at the Victoria and Albert Museum, London, UK, and concluded that the range of pigments was stable during the 16th and 17th centuries and began to expand in the 18th century through the introduction of synthetic pigments. Inorganic pigments used in three different hand-coloured, 17th century maps of Dutch manufacture, two of Portugal and one of the Iberian Peninsula, were studied by Mendes et al [66] This article contributes to a better knowledge of the techniques and palettes used for colouring of maps of this period.…”