THE RESEARCH PROJECT ON THE LAST JUDGEMENT TRIPTYCH BY HIERONYMUS BOSCH

COLLECTION OF THE GEMÄLDEGALERIE DER AKADEMIE DER BILDENDEN KÜNSTE WIEN

M. D. Colagrande 1, F. Cappa 1, A. Lehner 2, R. Trnek 2, M. Schreiner 1

1. Institute of Natural Sciences and Technologies in the Arts, Academy of Fine Arts, Schillerplatz 3, 1010 Vienna, Austria.

2. Gemäldegalerie der Akademie der bildenden Künste Wien, Academy of Fine Arts, Schillerplatz 3, 1010 Vienna, Austria.

IntroductionThe triptych The Last Judgement by Hieronymus Bosch, one of the most outstanding works of art in the collection of the Gemäldegalerie der Akademie der bildenden Künste Wien (Paintings Gallery of the Academy of Fine Arts Vienna), is currently the subject of a collaborative research project between art historians, conservators and conservation scientists, who investigated art historical aspects as well as issues of painting techniques. A complete documentation in the visible, infrared, UV and X-ray radiation range was performed using photographic techniques, the paint surface was examinated with a stereo-microscope and a range of samples was taken for cross-sections, which were analysed by optical microscopy, scanning electron microscopy with energy dispersive X-ray microanalysis (SEM/EDX) and Raman spectroscopy 1.

The technical examination aims not only to reveal the original painting technique but also to help clarify questions of conservation history and provenance.

Experimental and analytical techniquesOptical UV-Fluorescence Microscopy and Scanning Electron Microscopy with Energy Dispersive X-ray Microanalysis (SEM-EDX)The cross-sections were first analysed by optical microscopy in the visible and UV range (Zeiss, Axioplan 2 Imaging, Halogen HAL 100, HBO-Lamp 100). UV-fluorescence microscopy supports the identification of pigments as well as binding media, especially natural resins.

By these means, it was possible to study the layer structure of the original ground and paint layers, as well as later campaigns of overpaint. Furthermore, differences in the application of paint on the central panel and the wings suggest a division of work between the master and workshop assistants.

The cross-sections were then further analysed by scanning electron microscopy with energy dispersive X-ray microanalysis (SEM/EDX) on a Quanta 200 SEM with 20 kV voltage.

By detecting the elemental composition of the paint layers, not only certain pigments, like vermillion, azurite or lead tin yellow were identified with certainty. Also, this analytical technique helped to distinguish apparently similar whitish or greyish paint layers in the area of the coat of arms on the wings’ back sides, by their characteristic microstructure and inclusions of different black and red pigments, thus enabling us to better understand the changes in design of this area at different times.

Some pigments, like red lead and bone black were only found in non-original layers.

ConclusionsThe combination of optical microscopy, SEM-EDX and Raman spectroscopy showed that Hieronymus Bosch’s painting technique and his palette are typical for the 16th century, featuring chalk in the ground layer and traditional pigments such as lead white, carbon black, azurite for the blues, copper resinate for the greens, vermillion, iron oxides and red lakes for the reds, lead tin yellow and ochre for the yellows. 2,3

Furthermore we were able to differentiate the painting technique on different parts of the central panel and the outer wings, thus suggesting a division of hands between the master and his workshop. Also, later alterations and campaigns of overpaint have been identified and last but not least their date of execution roughly determined.

Acknowledgements FWF-Project No. P23848, Ing. Elisabeth Eitenberger and Dr. Johannes Hofner from the Institute of Chemical Technologies and Analytics of the Vienna University of Technology

1. J.M. Chalmers, H.G.M. Edwards, M.D. Hargreaves. Infrared and Raman Spectroscopy in Forensic Science. Wiley, 2012.

2. A. Roy. Artists´Pigments: A handbook of their history and characteristics. National Gallery of Art, OUP USA, 1993, Vol. 2.

3. R.D. Harley. Artists´pigments c. 1600-1835. Butterworths, 1970, pp. 70-81.

Figure 1: The Last judgement triptych by Hieronymus Bosch

Figure 2: Cross-section 579-2, taken from the area of the rock on the left edge of the left wing. Normal light, UV light, SEM micrograph and EDX spectrum. Underneath the greyish paint for the rock, there are blue and green underlayers, probably associated with the landscape.

Raman spectroscopyThe analyses were performed on a Raman spectrometer LabRAM ARAMIS Vis (400-1100 nm). The pre-viously prepared cross-sections were analysed using three different lasers: 633 nm/17 mW, 532 nm/50 mW, 785 nm/80 mW. With Raman spectroscopy some of the results of the SEM analysis could be confirmed, others corrected (such as the presence of lead-tin yellow instead of lead white in some green layers). It was also possi-ble to identify the green pigments with more precision and to determine the presence of copper resinate not only in the original layers but as well in the early overpaint (especially in the paradise wings), thereby suggesting that it was executed within the 16th century.

Figure 3: Raman spectrum of the blue crystal in layer 3 shown in Figure 2 confirming the presence of azurite. The reference spectrum is shown in blue, the real sample is shown in red.

Figure 4: Raman spectrum of the green layer 4 shown in Figure 2 confirming the presence of copper resinate. In blue the reference spectrum and in red the real sample are shown.

NTK - Naturwissenschaften und Technik in der Kunst] a [ akademie der bildenen künste wien