The unorthodox and unauthorised restoration in 2011 of a 16th-­century masterpiece, housed until recently in Colmar’s Musée Unterlinden, has divided experts and highlighted some glaring gaps in France’s management of its art treasures. The debate revolves around Mathias Grünewald’s Isenheim Altarpiece, which has been compared to the works of Leonardo da Vinci, Michelangelo and Raphael. France’s main restoration and conservation body is due to release a report on the condition of the polyptych this month, outlining recommendations for its treatment and future preservation.

The work attracts 200,000 visitors each year to the Alsatian town of Colmar; they are drawn by the power of the altarpiece as well as its extraordinary history (see box, p38). Long believed to have been the work of Albrecht Dürer, the altarpiece has influenced Romantic poets, Expressionist painters and Surrealist artists. The French Symbolist writer Joris-Karl Huysmans, for example, wrote of being “swept away” by this “typhoon of art”, and was particularly fascinated by “the fearsome nightmare of the Calvary” and the “awful horror of this huge Christ dominating the nave of the ­museum”.

Created in the 1520s for the Antonite monastery, a ­hospice in nearby Isenheim for plague victims and sick peasants, the altarpiece is formed of seven painted wooden wings, folded around a gilded reliquary carved in Strasbourg by the sculptor Niclaus of Haguenau. The panels depict scenes from the life of St Anthony and the New Testament, painted with a vivid imagination and a powerful harshness derived from the Gothic tradition of the Rhine Valley. They were actually the work of the German painter Mathis Gothart-Nithart (1475/80-1528), but a 17th-century art historian confused him with a man called Grünewald and the name stuck.

The Isenheim Altarpiece is on display, with Martin Schongauer’s Madonna of the Rose Bower, 1473, in Colmar’s Dominican Church for at least the next 18 months. The polyptych was moved last month because of building work on the museum’s chapel, which is being carried out as part of a controversial renovation and extension plan financed by the French government, the Alsace region and the town of Colmar. Relations between the town’s mayor and the Schongauer Society, which runs the museum, are strained; those between Alsace and the national authorities in Paris are historically mired in mistrust.

Safety concerns

The transfer of the altarpiece, which was delayed for months because of concerns over the work’s safety, was completed on 8 November. Because the altarpiece is the property of the state, the operation was supervised by the Centre de recherche et de restauration des musées de France (C2RMF), which imposed strict conditions.

“Moving such a monumental work sounds crazy,” admits the museum’s chief curator, Pantxika de Paepe, “but it had to be done to protect it. The chapel’s roof is crumbling and it would have been too dangerous to maintain the works in situ during the building work.”

A public spat erupted in 2011 when the museum, without seeking authorisation from the government, decided to restore the altarpiece—an intervention that some scientists did not deem necessary. Within six days, restorers had wiped off most of the varnish on The Torment of Saint Anthony and then revarnished it. They repeated the process on half ofSaint Anthony Visiting Saint Paul the Hermit, as a “test”. To put this into context, the Louvre took almost a year to lighten the varnish of Rembrandt’s Supper at Emmaus, 1648, and nearly two years to do the same for Da Vinci’s Saint Anne, to ensure the solvent would not damage the paintings. No specific scientific examination or evaluation was conducted before or during the 2011 intervention.

Varnish stripped down

The C2RMF was called in after a public outcry prompted Frédéric Mitterrand, then the culture minister, to intervene. Preliminary observations by the C2RMF showed that the restorers went about their task with gusto. The yellow varnish on the first panel, dating from 1946, was reduced to eight microns (around a tenth of a hair). On the second panel, it was stripped down to 4.3 microns. Some fear the solvent might migrate towards the top layers of paint.

Only a few small spots or “dots” have been measured, so it is impossible to tell if the varnish has disappeared altogether in other areas of the panels. But Paepe says this type of analysis “makes no sense” and maintains that the operation was justified. “If we could start over, we would do just the same,” she says.

Although the colours and details of the paintings are much more visible, it is likely to take some time to fully assess the impact of the intervention.

The dispute has divided experts, creating a rift between those who think restoration should be based on scientific studies and the old school, who have faith in experience and resent the criticism of their colleagues by the media. The French authorities have never managed to provide a technical framework or protocol for restoration in museums, but with tensions running high on all fronts, the Isenheim project is unlikely to bring this any closer. ***

Surviving revolutions and world wars

Astonishingly, the Isenheim Altarpiece (detail, below) came through the Reformation, and even the French Revolution, unscathed. In 1793, at the height of the Terror, when art representing kings or saints was under attack, the scholar and revolutionary Franz Christian Lerse had the work moved to a Jesuit monastery for protection. The panels, along with Martin Schongauer’s Madonna of the Rose Bower, languished there among the food stores and ammunition.

The altarpiece was moved in 1855 to a museum set up six years earlier in the Unterlinden monastery by the Schongauer Society. In 1917, occupying German forces sent the piece to the Alte Pinakothek in Munich, where it was briefly exhibited. It attracted big crowds and the attention of artists such as Max Beckmann, Otto Dix, George Grosz and Thomas Mann. The work was considered such an important symbol of German culture that it was more than a year after the end of the First World War before the piece was returned to Colmar.

In 1940, it was moved again for protection, to various castles in France. At one point, the truck in which it was being transported caught fire, but the paintings were not damaged.