Vasari's Last Supper reassembled 47 years after 1966 Florence flood

New restoration techniques mean 1546 painting could be ready for display by 50th anniversary of Arno bursting its banks

The last casualty of the devastating Florence flood of 1966 has been reassembled, raising hopes of a full restoration before the 50th anniversary of one of the greatest cultural disasters of modern times.

Giorgio Vasari's Last Supper, painted on five wooden panels and measuring about 2.5 metres by 6.5 metres (8ft by 21ft), was one of the most seriously damaged works to survive the flood. Dozens of people and millions of pieces of antiquity and works of art were lost for ever when the Arno burst its banks, raging through Florence in the worst flood since the middle ages.

In the decades since, new methods of restoration have been created to help salvage the damaged masterpieces.

Vasari's Last Supper was completely immersed in water for about 12 hours and the lower portion of the painting was under water for even longer. To help them dry, the waterlogged panels were separated. A paper treatment was applied to the paint itself to stop it from flaking off and being lost permanently.

The work remained in pieces for decades, with restoration experts at a loss to know how it could be put back together. But this week the Los Angeles-based Getty Foundation, which sponsored the reassembly of the painting, announced: "For the first time in 47 years, the five wooden panels that make up the storied painting are joined together again to make the artwork whole".

The operation, which began more than three years ago, was carried out at the Opificio delle Pietre Dure (OPD) in Florence and co-ordinated by its deputy director of painting conservation, Cecilia Frosinini. "We can now say that the painting has been saved," she said on Thursday.

Though best known as the author of the first great work of art history - Lives of the Most Excellent Italian Painters, Sculptors, and Architects - Vasari was a noted artist in his own right. The nuns of the Murate Convent in Florence commissioned him to paint a Last Supper in 1546.

In the 19th century, the painting was moved to the Basilica of Santa Croce, which is where it was on display when the river Arno burst its banks and the city was engulfed by floodwater.

Frosinini said the water shrank the panels and dissolved the glue that had been used, together with plaster, to provide a surface for the painting.

When the painted area and the panels were measured separately, it was found the wood had contracted by 3cm. "That is a vast difference in terms of restoration and for a long time the idea of restoring the painting seemed impossible," she said.

The conundrum was eventually resolved by taking advantage of the splits in the panels that had opened up as a result of the soaking that they received. "Tiny slivers of wood were inserted in the gaps in the panels to give them back their original dimensions," said Frosinini.

To restore adhesion to the surface, the OPD's experts used a glue made from sturgeons brought to Florence by Russian experts after the flood. The panels were reassembled using one of Vasari's original crossbars and others that were specially crafted. The Last Supper is now "absolutely restorable", said Frosinini. "We are now looking for a sponsor ready to fund the last part of the operation."

The Getty Foundation said the final conservation of the painted surface was expected to take at least two years. Frosinini said: "Our dream is to have the painting fully restored in time for the 50th anniversary of the flood in 2016."

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