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Among the artists’ materials of the nineteenth century, pastel crayons merit scientific interest since their early commercial formulations are mostly unknown and, until now, have been considerably less studied with respect to other contemporary painting materials. In this framework, research herein reports the results of a comprehensive multi-analytical study of 44 pastel crayons of two recognized brands (LeFranc and Dr. F. Schoenfeld) from the Munch museum collection of original materials belonging to Edvard Munch. The integrated use of complementary spectroscopic and hyphenated mass-spectrometry techniques allowed the compositional profiles of the crayons to be traced providing the identification of the inorganic and organic pigments, the fillers/extenders and the binders. All crayons resulted to be oil- based and the binder was identified to be a mixture of a drying oil (safflower or linseed oil), palm oil or Japan wax and beeswax. Among others, pigments such as ultramarine, chrome yellows, Prussian blue, manganese violet, viridian and madder lake have been identified. A significant alignment in formulations of the brands was observed with the only exception of the greens which showed distinctive pigment and filler compositions. The analytical information provided for these commercial artists’ materials will be of great interest for academia, museum and other institutions hosting art collections dating from the same period and it will be used by the Munch museum to draw proper conservation strategies of its own artwork collections.

Geranium lake is an eosin-derived organic pigment highly employed by Van Gogh and his contemporaries. Its elusive behavior, observed in a large number of post-impressionism masterpieces, is of current concern for both conservators and heritage scientists. Herein, the lightfastness of Geranium lake within oil matrix has been investigated by means UV–Vis spectroscopic techniques and HPLC-DAD-HRMS with the final aim of understanding the degradation mechanism behind its marked bleaching. Accelerated photo-aging experiments irradiating with mono/polychromatic light have been carried out on oil paint models prepared with lead eosin-based lakes, in-house synthesized for this purpose according to available historical recipes, alone and in admixture with different white pigments namely, zinc oxide and basic lead carbonate. The aging experiment not only reproduced the fugitive nature of Geranium lake but also evidenced a reversible behavior during the preliminary stages of the light exposure. Succeeding targeted experiments employing monochromatic light as well as a simplified eosin-oil system in solution, corroborated by the wide literature regarding the photophysics of xanthene dyes, allowed us to propose a reasonable fading mechanism of eosin-based lakes, based on the key role played by linseed oil and environmental oxygen.

The identification of natural dyes in ancient textiles is a longstanding challenge for scientists; yet, the effort honours the skill and knowledge of master dyers by retracing traditional dyeing methods and assisting in conserving historical treasures for future generations. Here, the main constituents of selected native Japanese extracts from the roots of Lithospermum erythrorhizon and Scutellaria baicalensis, the barks of Phellodendron amurense and Morella rubra, the dried flower bud of Syzygium aromataticum, and the fruit of Terminalia chebula are determined by surface-enhanced Raman spectroscopy following traditional Japanese extraction methods. The analytical amalgamation of data from SERS examinations on crude extracts and on subsequently refiltered and diluted extracts provides further effective and sensitive results for the combined identification of napthoquinones (shikonin and alkanin), alkaloid (berberine), polyhydroxyflavonoids (baicalin/baicalein, myricetin/myricitrin), diarylheptanoids, allylbenzene (eugenol), and tannins (gallic/ellagic acid). The comparison of results from this analytical protocol with those achieved by the more traditional chromatographic and mass spectrometric method provides and questions data regarding generally accepted marker components and enantioselective discriminations that serve to enrich the database of biological sources of colouring materials to be used in determining historically important Japanese colorants and dyestuffs.

Chemical analysis of ancient residues of pharmaceutical or cosmetic preparations such as balms or ointments is made problematic by the high complexity of these mixtures, composed of organic and inorganic materials. Consequently, a multi-analytical approach and special caution in the interpretation of the results are necessary. In order to contribute to the improvement of analytical strategies for the characterization of complex residues and to reconstruct ancient medical practices, a replica of a pharmaceutical formulation of the seventeenth century was prepared in the laboratory according to a historically documented recipe. In a round robin exercise, a portion of the preparation was analysed as a blind sample by 11 laboratories using various analytical techniques. These included spectroscopic, chromatographic and mass spectrometric methods. None of the laboratories was able to completely reconstruct the complex formulation, but each of them gave partial positive results. The round robin exercise has demonstrated that the application of a multi-analytical approach can permit a complete and reliable reconstruction of the composition. Finally, on the basis of the results, an analytical protocol for the study of residues of ancient medical and pharmaceutical preparations has been outlined