Dog x-rays, art history and a ‘never say never’ attitude: the surprising toolbox of professional conservators

When Cecilia Giménez noticed a flaking and faded painting on the wall of her local church in 2012, her decision to pick up a paintbrush would result in one of the world’s most infamous cases of art restoration.

The Spanish octogenarian’s Mr Bean-like job on the 20th century fresco, done “spontaneously and with good intentions”, turned Jesus into something resembling a “bloated hedgehog” and “a crayon sketch of a very hairy monkey in an ill-fitting tunic”.

It’s little wonder that Giménez’s attempted revamp, which came to be known as Monkey Christ, was doomed to failure; spend any time with professional conservators and you soon realise how delicate and difficult art conservation is.

In some instances of bungled restoration, big blunders can’t be salvaged. But often, conservators can undo the damage, even when deterioration or changes are extreme – as in the case of a Spanish statue that was comically botched in 2018 and then painstakingly fixed.

“We see all sorts of things with large tears and discoloured varnishes and paint falling off [to the point] where you can hardly breathe next to a painting,” says Cushla Hill, senior paintings conservator at the Grimwade centre for cultural materials conservation at the University of Melbourne. “We’ve had paintings from Warmun up in the Kimberley that have gone through a serious flood … that we’ve been able to salvage.

“If something’s burnt beyond repair that’s probably a write-off, but never say never,” Hill says.

Conservators work at the junction of art and science, marrying technical expertise with an understanding of art history. In the National Gallery of Victoria’s vast conservation wing, paintings are propped on easels beside microscopes and state-of-the-art imaging equipment.

“Anything we do should be reversible,” says Michael Varcoe-Cocks, the NGV’s associate director of conservation. One of the basic tenets of conservation is that restorative work should use materials that are clearly distinguishable from the original work, so that the repairs can be undone in future.

Where chemically similar compounds have been used is when conservators run into trouble. Varcoe-Cocks recalls a headache of a restoration of an 1890 Arthur Streeton painting, on which the varnish layer had yellowed and needed replacing.

“We realised that the varnish wasn’t a natural resin varnish that the artist had applied,” Varcoe-Cocks says. An earlier restorer had slathered on a layer of Estapol, a synthetic floor varnish, which couldn’t be easily removed without also dissolving the paint layer underneath.

There was a discussion about whether to accept the painting was a lost cause – but after six months, Varcoe-Cocks figured out a way to lift the varnish using a solvent gel, working with a stencil and a timer: 1.5cm square by painstaking 1.5cm square. “It was horrible. It was a year of my life,” he recalls. “But it was a good outcome.”

The NGV’s team of 33 conservators – the largest of any institute in the southern hemisphere, according to Varcoe-Cocks – is responsible for some 78,000 works in the gallery’s collection. They manage that immense figure through a combination of preventive conservation – relative humidity is maintained at around 50%, and the temperature at 21C – and prioritising which works need interventive attention.

Varcoe-Cocks is about to restore an 1887 work by the Scottish painter William Orchardson. The First Cloud depicts an arguing couple: a woman is walking out of the scene, leaving behind a forlorn man in a lavish sitting room.

Varcoe-Cocks will replace the painting’s now discoloured 19th-century varnish, which has yellowed the woman’s dress and the man’s shirt. “We can’t see it easily with our eye, but under UV light you can see very easily,” he says.

On a nearby computer, he pulls up an image taken by infrared camera. Infrared, which is good at detecting carbon, shows the initial pencil sketches that underlie the painting: a chair that was initially simpler, and a huge rug over the floor, absent in the final work to strand the man on a little fabric island.

“The change from the sketch to the painting … that’s a choice the artist has made,” Varcoe-Cocks says, adding that being able to reveal the layers underneath is useful to understand an artist’s working methods.

Scientific imaging techniques can reveal astounding details. Hill and the conservation team at the University of Melbourne will send paintings for x-ray if they suspect there is another painting hidden under the surface layer. “We have access to an x-ray through the vet school – either the dog or the horse x-ray depending on the size of the painting,” she says.

They also use x-ray fluorescence, “which is like a ray gun, really” – it shoots a laser into a painting and can pinpoint the specific elements that make up a pigment. “It’s quite good for when we’re authenticating paintings. If we detect titanium, which is a 20th century pigment in a painting that’s purported to be Renaissance or much earlier … if it’s not in an area of restoration, we know it’s potentially a fake,” Hill says.

Related: It’s a botch-up! Monkey Christ and the worst art repairs of all time

For those wanting to look after their own personal collections of art and photographs, conservators have some basic tips, though Varcoe-Cocks emphasises that advice varies depending on the type of work. “Don’t put them in direct sunlight, don’t put them above the heater,” he says.

Hill says: “Things like backboards on a painting can be a really cheap form of insurance. It creates a little microclimate behind the painting, and you don’t get dust and dirt collecting behind the canvas.”

A layer of glazing can help prolong a work’s lifespan. “We see paintings from the 1930s that have been glazed their whole life, and they’re in amazing condition.”

Above all, she says: “Keep it on the wall and love it.”