Mix of metals in this Picasso sculpture provides clues to its mysterious origins

AUSTIN, Texas — An analysis of the metals in dozens of Picasso’s bronze sculptures has traced the birthplace of a handful of the works of art to the outskirts of German-occupied Paris during World War II.

This is the first time that the raw materials of Picasso’s sculptures have been scrutinized in detail, conservation scientist Francesca Casadio of the Art Institute of Chicago said February 17 at the annual meeting of the American Association for the Advancement of Science. And the elemental “fingerprints” help solve a mystery surrounding the sculptures’ origins.

“In collaboration with curators, we can write a richer history of art that is enriched by scientific findings,” Casadio said.

Casadio and colleagues from the Art Institute of Chicago and Northwestern University in Evanston, Ill., studied 39 bronzes in the collection of the Picasso Museum in Paris. The team used a portable X-ray fluorescence spectrometer to record the amount of copper, tin, zinc and lead at several points on each sculpture.

Based on the percentage of tin versus zinc in the bronze, “we found that there are compositional groups that relate to a specific foundry,” Casadio said. Seventeen sculptures had a foundry mark on them, so the researchers could relate metal mixes to specific foundries.

But seven sculptures lack foundry marks. Based on their composition, researchers pegged five to a specific foundry — that of Émile Robecchi, a craftsman whose workshop sat in the southern outskirts of Paris. Original invoices from the foundry surfaced two years ago and revealed when some of the pieces were cast. For instance, the description, weight and size written on one invoice confirmed that the bronze of Tête de femme de profil (Marie­Thérèse) — a portrait of one of Picasso’s mistresses originally sculpted in plaster in 1931 — was cast at the foundry in February 1941.

At that time, the war had been under way for years and the Germans had just occupied Paris. Picasso worried that his fragile plaster sculptures could be easily destroyed and sought to have them cast in bronze.

The team’s analysis also found two distinct mixtures of bronze that came out of the Robbechi foundry. That difference makes sense in the context of 1940s occupied Paris, when the Germans instituted laws requiring that people turn in certain metals to go toward war efforts, Casadio said.

“A lot of [foundries’] archives are incomplete or nonexistent,” Casadio said. The new analysis “reinforces why it’s really important to collaborate and how science adds the missing piece of the puzzle.”