Paintings can sit on a wall for centuries and still hold onto bright colours and fine detail. For many works across Yorkshire, that comes down to a Sheffield studio where conservators remove old damage and repair them with modern methods.

Critchlow & Kukkonen Ltd is a painting conservation and restoration business run by Eeva Kukkonen and Lucy Critchlow. The studio works on art dating back to the 16th Century and has restored pieces for Hull Maritime Museum, Sheffield Museums Trust and National Trust properties including Beningbrough Hall in York and Nostell Priory in Wakefield.

“There’s often decades or hundreds of years of discoloured, dark brown varnishes so the colours are disguised,” Eeva Kukkonen says. “It’s always really satisfying to bring something back to how the artist intended it.”

The work can take days or months. One recent project took more than 700 hours.

The studio uses synthetic materials such as varnishes. Paintings are usually stripped of older restoration work and treated with newer, reversible methods.

“People used to use materials to restore paintings that weren’t quite up to scratch, such as oil paint. Hopefully what we do now isn’t going to degrade as badly,” Eeva says.

She says each painting reacts differently to the solvents used in the process, which “keeps you on your toes”.

The aim is not to add new artistic touches. Restorers are “dealing with damage” only, she says.

“The ethics of conservation is quite an important issue these days. You shouldn’t be tampering with the original piece of art,” she says.

“[In the past] there wasn’t really a conservation training as such, though people who would have been fixing paintings would have been painters and artists.

“They might have had a more liberal touch, so if there was fairly small damage in the sky, instead of just retouching, sometimes people just repainted the entire sky.”

Eeva says landscapes and historical scenes are a favourite, especially when they show a local area and how it has changed over time.

“Because we’re in Yorkshire, there’s quite a lot of artists that become familiar, because they’re in a lot of collections.

“There’s a lot of local artists, as well as bigger national names that come up.”

The paintings also vary in size. The studio has worked on a painting by 17th Century artist Sir Thomas Lawrence and a portrait of King James II at Castle Howard.

“We also get a lot of portraits, especially of old men,” Eeva jokes. “So when you get a portrait of a woman it’s quite exciting to give some airtime to women in history.”

One of the studio’s latest projects was restoring a painting of Kirkstall Abbey for Leeds Museums and Galleries. The work, by an unknown artist, was donated in 1958 and had spent at least the past 25 years in storage because of its condition, curator Kitty Ross says.

“The [damaged] paintings have to be more or less hidden even from people looking at them. If they’re in store, then they’re not of any great use,” she says.

A grant from Friends of the Leeds City Museums paid for the restoration, which Kitty described as “pretty exciting”.

She said it was not the first Kirkstall Abbey painting Eeva had restored for the museum. One earlier painting was in such poor condition that its subject was unclear before treatment.

“For years, we didn’t know what it was, is it a dog? It was a complete gamble,” Kitty adds. “That was even more exciting.”

Eeva says she often spots the studio’s work when visiting stately homes and museums.

“It’s really nice to see, because we look at them out of the frame [and] we’re all perfectionists, we could keep working on them for ages.

“When you see it in its place in a house or a museum, back in its frame and on the wall with other pictures, they just look different there. It’s a nice feeling.”

She says it can also feel like a “busman’s holiday” because it is “hard not to look at the problems in paintings”.

“You just start to peer at them at an angle to see if there’s any flaking paint,” she adds. “It’s quite hard to stop, so I often enjoy going to contemporary art museums because I don’t have that problem looking at sculptures or something like that.”

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