Egg vs. Oil in the Cookbook of Plasters: Differentiation of Lipid Binders in Wall Paintings Using Gas Chromatography-Mass Spectrometry and Principal Component Analysis.

Wall paintings are integral to cultural heritage and offer rich insights into historical and religious beliefs. There exist various wall painting techniques that pose challenges in binder and pigment identification, especially in the case of egg/oil-based binders. GC-MS identification of lipidic binders relies routinely on parameters like the ratios of fatty acids within the plaster. However, the reliability of these ratios for binder identification is severely limited, as demonstrated in this manuscript. Therefore, a more reliable tool for effective differentiation between egg and oil binders based on a combination of diagnostic values, specific markers (cholesterol oxidation products), and PCA is presented in this study. Reference samples of wall paintings with egg and linseed oil binders with six different pigments were subjected to modern artificial ageing methods and subsequently analysed using two GC-MS instruments. A statistically significant difference (at a 95% confidence level) between the egg and oil binders and between the results from two GC-MS instruments was observed. These discrepancies between the results from the two GC-MS instruments are likely attributed to the heterogeneity of the samples with egg and oil binders. This study highlights the complexities in identifying wall painting binders and the need for innovative and revised analytical methods in conservation efforts.

A Multianalytical Approach for the Characterisation of Materials on Selected Artworks by Monogrammist IP.

This paper presents an investigation of wooden artworks from the collection of the National Gallery Prague created by Monogrammist IP-one of the top carvers of the Salzburg-Passau region at the beginning of the 16th century. His wood reliefs were examined to gain a better understanding of the historical techniques used in medieval art workshops. The internal structure of the small relief Visitation was analysed using computed tomography. Tomographic reconstruction made it possible to distinguish wood species, observe the internal structure of the artwork in detail, study the technological procedures and identify earlier repairs, additions and damages. Tomographic investigation proved the use of four types of wood on the relief Visitation, most likely pear, lime, unspecified softwood and other different species used for joining dowels. A combination of non-invasive and micro-destructive analytical techniques was employed for the chemical characterisation of the materials in the surface layers of the artworks. Photomicrographs of the surface were taken to provide material for the initial investigation. Non-invasive material research was conducted using a portable X-ray fluorescence analyser and, in selected cases, an external reflection infrared spectrometer. The detailed analyses on the micro-samples was carried out by optical microscopy, micro-Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry and gas chromatography with mass spectrometry. A glaze layer based on protein with earth pigment was identified on the relief Christ the Saviour from Death.

Searching for blood in Chinese lacquerware: zhu xie hui.

The study gives an overview of the tests and analyses undertaken in the past 20 years to establish the presence of blood in the foundation layers of Chinese lacquer artefacts and also shows the development of analytical methods over that period. When undertaking the conservation of lacquer objects it is crucial to know the type of binding medium as this influences the selection of any consolidants that may be required in the treatment. Microchemical tests to identify blood using benzidine and luminol, various chromatographic and mass spectrometric techniques and DNA analyses were assessed on selected Chinese lacquer objects, and the results gained are summarized.

Methodology and application of gc-ms to study altered organic binding media from objects of the Kunsthistorisches Museum, Vienna.

Within the Kunsthistorisches Museum (KHM), Vienna, three off-line GC-MS analytical procedures for the identification of natural organic media have been refined, tested, and validated on a series of reference materials (partly artificially aged) to apply this knowledge for investigations of original, historic works of art from the museum's collections. At first, a set of artificially aged mockups has been prepared and a reference database has been built up for the identification of drying oils, resins, waxes, proteins and polysaccharides. Some interesting observations concerning the alteration of the composition of these organic media during different ageing steps are presented in the following text. In addition, some selected examples for the application of the refined techniques for the analysis of real samples from various museum objects are shown.

Direct chemolysis-gas chromatography-mass spectrometry for analysis of paint materials.

A novel direct method using (m-trifluoromethylphenyl)trimethylammonium hydroxide (TFTMAH) has been developed for on-line (trans)esterification of lipidic materials (drying oils, egg) prior to GC-MS analysis. The method was first optimised by comparing three N-methylammonium hydroxide reagents (TMAH, PhTMAH, TFTMAH) and triolein as a lipid standard. Secondly, the procedure was tested on a series of fresh and naturally aged (up to 40 years) (un)pigmented drying oils and egg yolk reference film standards. Thirdly, the method was applied to the analysis of a sample from an altar painting "Resurrection of Christ" by Francesco Solimena (1723) from the Chapel of Upper Belvedere in Vienna. The relative proportions of the fatty acids from the translucent size layer confirm the presence of partially degraded oil, probably prepolymerised walnut oil.