An art project at the Hugh Lane gallery in Dublin has led to the discovery of three unseen paintings, including work from a post-impressionist master.

Ben Geoghegan, a Galway-based artist, has been photographing the backs of paintings for several years and recently shot 18 works from the gallery.

He unearthed two paintings by Paul Henry, one of Ireland’s most celebrated artists, and a post-impressionist work by the French painter Edouard Vuillard.

A beach scene was found on the rear of The Mantelpiece, a 1905 Vuillard work. The “hidden painting” had only been seen by museum staff moving the work.

The drawing, shown here for the first time, depicts three people and a dog at the seaside. The work appears finished and has its own glass cover and frame.

While artist signatures, gallery stickers and wear and tear constituted most finds, Geoghegan also discovered two paintings on the back of Henry’s Turf Bog Scene, painted between 1916 and 1919 while living on Achill.

The landscape scene and portrait of two women had no covering, so have suffered damage.

Geoghegan said he undertook the project to give familiar works a new dimension, but had not expected something so “fantastical”. He said: “I found a lot of provenance and sometimes notes from the artist. Also legal documents. Owners and buyers also added bits and bobs.”

Niamh O’Sullivan, a professor of visual culture at the National College of Art and Design, said it was once quite common to reuse canvas or boards. “Artists worked through their ideas ‘verso’, bringing the painting to completion ‘recto’,” she said.

Philip McEvansoneya, an art history lecturer at Trinity College Dublin, said artists had a tradition of painting over an abandoned work or turning the canvas over. “Painting over the front is more common, because if the canvas is reversed then it has to be taken off the stretcher and remounted,” he said.

“The images which ended up on the back have not been much studied as they have clearly been dismissed in favour of what’s on the front. Sometimes sketches may be found on the back rather than semi- or wholly finished paintings.”

He said the Vuillard had interesting features of impasto and scratching with the brush tip and was likely to have been the result of one period of work, put aside and never returned to.

Geoghegan also photographed the reverse of paintings by Claude Monet, Edouard Manet, Patrick Collins, Jack B Yeats and James Whistler. Photographs of the back of John Lavery’s portrait of Major Compton-Smith and Sam Bough’s

Kilchurn Castle are on show at the Hugh Lane as part of the Other Men’s Flowers exhibition.

On the reverse of Waterloo Bridge by Monet, one of the gallery’s most popular pieces, he found “very distinctive archival devices” because the Tate recorded it. These included an intact wax stamp to protect against forgery by alerting curators to any attempt to open the frame back.

Michael Dempsey, the head of exhibitions at Hugh Lane, said: “The back has an aesthetic relevance. It shows what materials are used, how it was stored and how it has deteriorated.”

Geoghegan is negotiating an exhibition space for all 18 works, including the unseen paintings. The photographs are ultrachrome inkjet prints, devised to look as real as possible.

The project also raised a copyright issue. In 1998, a US court ruled that photographs of paintings were not original and the owner of the painting had all copyrights. No such case has come before the Irish courts.

The Hugh Lane wanted copyright to Geoghegan’s work, but after employing a lawyer, he secured the rights. The matter was further complicated by uncertainty over the copyrights of the backs of paintings.

Dempsey said this “grey area” was being explored and that Hugh Lane would argue that if they, or an estate, own the copyright to the image then they also have the rights to the reverse.

Times Recommends

• Michael Jackson: Not the final chapter
• Indian Army spends10m rupees on golf buggies
• Brüno toned down for 15 rating