AMSTERDAM (AFP).- Like watching paint dry? Soon art lovers will be able to watch one of the world's most famous paintings being restored live and online.

Rembrandt's masterpiece "The Night Watch" will undergo a years-long, multi-million-euro overhaul at Amsterdam's Rijksmuseum under the full gaze of the public.

Restorers will work in a "state of the art clear glass chamber" so visitors can see the 17th century classic receive its makeover -- a process that normally happens in secret.

The unique project starting in July 2019 is the biggest in the Rijksmuseum's history, General Director Taco Dibbits said on Tuesday.

"The Night Watch by Rembrandt is one of the most famous paintings in the world and we feel we have to preserve it for future generations," Dibbits told AFP.

"Over two million people a year come to see The Night Watch, it's a painting that everybody loves, and we feel that the world has the right to see what we will do with it."

The last major restoration work was carried out 40 years ago after a mentally ill man slashed it with a knife.

Since then experts have noticed a white haze appear on some parts, especially in the area around the knife damage, where it is bleaching out the figure of a small dog.

'Share this moment'
Rembrandt Van Rijn was commissioned in 1642 by the mayor and leader of the civic guard of Amsterdam, Frans Banninck Cocq, to paint the picture of the officers and other members of the militia.

The groundbreaking picture is the first of its kind to show such a group in motion, rather than in static poses, and features the interplay of light and shadow that the Dutch master is famed for.

The Night Watch -- also remarkable for is huge three metre by four metre size -- is now the Rijksmuseum's most famed exhibit, taking pride of place in its "Gallery of Honour".

Experts will examine the painting using high-resolution photography and computer analysis of every layer including varnish, paint and canvas before deciding on the best restoration techniques.

The work will then take place in a glass case designed by French architect Jean-Michel Wilmotte, who was behind revamps of both the Rijksmuseum and the Louvre gallery in Paris.

It will also be livestreamed "so everyone, wherever they are, will be able to follow the process online", said Dibbits.

"Conservation is usually done behind closed doors, but this is such an important painting, we feel that the public who owns it has the right to see it and we want to share this very important moment."

Knife and acid attacks
Over the last three centuries the painting has endured vandalism, restoration attempts and an escape from the Nazis.

In the 1700s large chunks were cut from each side during a move, followed by several bouts of work on the varnish that darkened the picture and helped give it its name.

In 1911 a man stabbed it with a knife, then in September 1939 the painting was evacuated from the Rijksmuseum as Nazi Germany closed in and hidden in a cave. After the war in 1945 it needed major restoration.

But the painting's sufferings were not over: the 1975 attack saw a disturbed man slash the painting 12 times, with traces still visible today.

The museum decided to carry out a major restoration then, only for a man to spray acid on it in 1990.

Recently, however, new problems emerged.

"We noticed that over the past years there's a white glare that appeared on the bottom part of the painting. We want to be able to understand what that is," said Dibbits.

Restoring "The Night Watch" will not be cheap, or quick.

"That will cost several millions," said Dibbits, adding that the museum would also be looking for private funding.

The Night Watch will be the centrepiece of an exhibition marking the 350th anniversary of Rembrandt's death starting in February 2019, before restoration work begins in full in July.

"As we say in Dutch, conserving paintings is a monk's job," said Dibbits. "It takes a lot of patience, so it might be several years."


© Agence France-Presse