Synthetic organic pigments in contemporary Balinese painting: a Raman microscopy study

Abstract

The colour palette from two 20th century and one 21st century Indonesian paintings from the island of Bali was determined by Raman microscopy. There is very little information concerning the artistic techniques from this region of the world and the influences in materials introduced by western artists. The most interesting finding of our study was the increasing substitution of natural pigments by modern synthetic organic pigments. The findings were also compared with samples of representative pigments commonly used by Bali artists, donated by a renowned Balinese painter. Raman microscopy, combined with Fourier transform infrared spectroscopy, high‐performance liquid chromatography and μ‐EDXRF, was able to separate the different components on several colours, and to identify both synthetic organic pigments and inorganic components. Three azo pigments from the diarylide subclass, PY 83, PY 55 and PO 16, were identified on the yellow, brown, red and orange colours. A copper phthalocyanine blue PB 15:x and a basic dye BB 26 were responsible for the blue colours, the former admixed with ultramarine blue. Goethite was sometimes introduced to create the green colour. Two other basic dyes, BY2 and PG 4, were the main chromophores of the yellow and green samples of local pigments. The inorganic pigments comprised bone white, bone black, carbon‐based black pigment, haematite, goethite, vermilion, ultramarine blue and anatase. Finally, the ground layer of all the paintings was identified as rice starch, with a double function of a white pigment. Copyright © 2012 John Wiley & Sons, Ltd.

SERS spectrum of red dyes in the Mapuche belts from the beginning of the XXth century

“…. The following spectral assignment based on published data and those reported by Colombini et al in PO36 and by Suwaiyan et al in benzimidazole and Krishnakumar et al in the fragment 2‐hydroxybenzimidazole, supports the present proposition. The most intense SERS bands of the sample 3357 at 1605 and 1144 cm −1 are attributed to νCO/νCC arom.…”

“…The spectral analysis of the SERS spectra was performed on the basis of Raman data on related molecular systems, [48][49][50][51] and on previous [46] and our own theoretical Raman data for PR57. The present Raman spectrum of PR57 is shown in Fig.…”

The use of Raman microscopy and laser desorption ionization mass spectrometry in the examination of synthetic organic pigments in modern works of art

“…XRD in combination with Raman spectroscopy has been used in the analysis of pigments in acrylic, alkyd, and oil tube paints . Raman microscopy along with FTIR and high‐performance liquid chromatography was used in the characterization of pigments used in contemporary Balinese paintings . FTIR and Raman microscopy have also been used in combination to examine pots of custom‐made paints used by the artist Sam Francis .…”

Spectral investigations on 1000£ banknotes throughout Italian Republic

“…The 1332 cm À1 vibration involves in-phase ZnÀ ÀN stretches coupled with both indole and benzene ring deformations [25]. The two bands at 737 and 672 cm À1 are assigned to the breathing vibration of the macrocycle structure of the phthalocyanine [22]. Phthalocyanine pigments, in particular copper phthalocyanine (CuPc), were also detected in blue printing inks on lira banknotes from trial print runs from the Economy Bank of Rijeka, Istria and Slovenian Littoral (1945)(1946)(1947) [20].…”

“…It represents the oldest and largest group of organic synthetic pigments and its presence in 1000 £ issued in 1962 demonstrates an important change in the manufacture of red inks. In particular, red pigments belong to the naphthol AS subclass of the azo pigment with good properties of lightfastness [22]. The band at 1582 cm À1 can be assigned to the naphthalene structure as for the 986 and 726 cm À1 absorptions [21], while the signal at 1484 cm À1 is the stretch of the À ÀN¼NÀ À group [21]; the strong peak at 1332 cm À1 is related to the presence of an aromatic nitro group and the CÀ ÀN symmetrical stretch is evident at 1115 cm À1 [21].…”