Identification of color pigments in wall paintings of Oscar Schlemmer

Residuals of wall paintings from Bauhaus artist Oscar Schlemmer have been re-discovered recently. The restauration strategy of these precious objects requires a phase identification of the color pigments. The study includes the identification of potential decomposition mechanisms, as the wall paintings were in contact with chemicals of the glue from overlaying wall paper. Some coloring minerals were identified by combining high-resolution powder diffraction (PXRD) and x-ray fluorescence spectroscopy (XRF) using the new diffractometers at the Rossendorf Beamline (ROBL).

The Bauhaus revolutionized creative and artistic thinking and work worldwide. Walter Gropius employed a series of acclaimed artists as professors, among them Oskar Schlemmer, Wassili Kandinsky, Lyonel Feininger and Paul Klee. Adolf Meier, head of the architectural office of Walter Gropius, commissioned Oskar Schlemmer with wall paintings in his apartment for the first Bauhaus exhibition in 1923. Oskar Schlemmer, who was 1922-1925 the head of the Bauhaus studio for wall paintings, performed the work with Werner Gilles. During the Nazi regime, Schlemmer’s work was classified as degenerate art. Many of his wall paintings were overpainted. The wall paintings in Meier’s former apartment fell into oblivion. It was in the 1990s that Bauhaus research became aware of the existence of these wall paintings, which are only documented by two black and white photos from the time they were created.

In 2018, the apartment became subject of restoration studies. For this purpose, a network of institutions was created to identify the color scheme of the wall paintings and to generate a detailed 3D model of the room. The identification of the original color substances of the paintings remains a demanding issue as there are only residuals available. Schlemmer used partly new organic color material which was identified by spectroscopic techniques. A part of the paints is based on natural or synthetic mineral phase. These substances appear usually in a crystalline form and were identified with XRD. Heavy metals were identified with XRF spectroscopy. The small size of the color fragments, which were released from the walls, have microscopic dimensions of 10-30µm. This makes it impossible to perform phase identi¬fication with conventional laboratory equipment. The results of the synchrotron based XRD and XRF measurements from ROBL will be presented.