M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)

Analysis - WITTMANN Zsuzsa, BÉLAFI-RÉTI Katalin, DÉCSY Zoltán, ERDŐHALMI-TÖRÖK Klára, KISS—BENDEFY Márta, VASSÁNYI István, VELLEDITS Lajos: Examination of painting materials used by Mihály Munkácsy for his painting "Studio"

While Rembrandt could, in fact, use it in thin layers for the final coating of some of his works without any problem, when painters used it in a greater quantity or as a ground, it resulted in browning and crackening, e.g. the 18th century English school. Gencault, Makart [2,3]. Masschelein—Kleiner [4] summarizes the materials which may refer to the origin of the mentioned "thick bitume". This material consists of the black remainder from the distillation of plants and animals and it is called tar, and the crude oil from this is named bitumen. A distinction is made between natural and synthetic asphalts by Wolbers [5 j. Certain characteristic absorption bands in the infrared spectra, namely those for substi tuted aromatics, may be useful analytically in distinguishing these materials from the resinous binding media. According to Wolbers bitumens are those carbohydrates which can be dissolved in CS2 and which, together with the CS2 insoluble or inert materials, forms the asphalt. The ratio of these inert materials depends on the place of occurrence (Trinidad, Syria, etc.) The materials known as asphalt, bitumen and tar are used interchangeably with not an exact content in the painting. The chemical composition of the dark ground so called "bitume" written about by Malonyay and other sources in the literature is unknown. It is indispensable that the restorer know the compositions of the pigments and mainly the "bitume" ground used by Munkácsy, and in many cases the determination of the original colour of a part is also essential. We regarded the analysis of the composition of the asphalt or bitumen used by the painter as the most important in our present work. Knowledge of the grounding material can better contribute towards clarifying the cause of the darkening process. Without this information it is impossible to preserve the pictures. In this paper the results of the first experiments of the above described task are summarized. 3. Sampling The places of the sampling and colours are shown in Table 1. Table 1 The places of the sample-taking Number The place of the sample (cm) Colour of sample 1 50x2 brown 2 100x101 brown 3 57.5x56 brown 4 147x edge red 5 80x edge brown 6 140x131 blue 7 left side edge ground I+II 8 left side edge ground I 9 left side edge ground I 10 left side edge ground I 11 53x132 brown