When Thomas Schuhbauer discovered a painting in his parents' home—a 1966 wedding gift—he found more than a pleasant Munich landscape. Hidden beneath the visible brushstrokes of Erich Mercker's "München am Odeonsplatz" lay an entire history of reckoning with the past: a Nazi flag painted over with blue and white, soldiers erased from the memorial, wreaths and raised arms buried under titanium white pigment. Now, X-ray fluorescence analysis has revealed what Mercker himself concealed nearly eight decades ago.
Mercker, a Munich painter who lived from 1891 to 1973, had built a successful career painting works filled with Nazi symbolism between 1933 and 1945. His "Die Stätte des 9. November" depicted the Feldherrnhalle monument, which commemorated the National Socialist German Workers' Party's failed coup attempt in 1923. After the war ended, like many German artists, he simply continued working—but he reworked his own history. He repainted the same motif under new titles like "Feldherrnhalle" or "München am Odeonsplatz," stripping away soldiers, wreaths, and the swastika flag, replacing it with the Bavarian flag instead.
The painting in Schuhbauer's possession showed all the hallmarks of this revision: the Bavarian flag, the monument still visible, no soldiers or wreaths. Yet something didn't fit. The monument had been destroyed immediately after the war ended—so how could it appear intact in a painting Mercker claimed was postwar? Schuhbauer contacted the Helmholtz-Zentrum Berlin (HZB) and connected with physicist Dr. Ioanna Mantouvalou, an expert in X-ray fluorescence spectroscopy who works at both HZB and TU Berlin's SyncLab research group.
XRF analysis works by identifying elements in materials without damaging them, penetrating a few millimeters below the paint's surface. What Mantouvalou and her team found was unambiguous: beneath the Bavarian flag lay a Nazi flag in red. Wreaths adorned the monument in the hidden layer. Two soldiers stood guard. Passersby raised their arms in salute. All of it had been systematically covered with oil paints containing significant amounts of titanium white—a pigment that appears nowhere else in the visible painting, yet was found among Mercker's own paint tubes, labeled "Titanium White 10103 Schmincke."
The revision appeared hasty. Traces of red paint from the original flag bled through at the edges. The upper monument remained visible despite being painted over. These inconsistencies suggest Mercker had worked quickly or carelessly, perhaps eager to transform his Nazi-era works into acceptable postwar paintings. As the researchers note in the journal Heritage Science, many German artists faced little criticism for their wartime collaboration until well into the 1960s—giving Mercker both motive and opportunity to quietly alter his past.
The discovery unites an unlikely team: a filmmaker, a physicist, an art historian, and a family descendant. "We had very different areas of expertise and backgrounds," Mantouvalou reflects. "We realized just how much of a barrier technical jargon can be. We had to get really creative to make sure we actually understood each other." The painting now resides in the Munich Documentation Centre for the History of National Socialism, where its hidden layer tells a story Mercker tried to paint away.