SCIENTISTS working at York Minster have cooked up a unique solution to the problem of acid rain eroding the building’s medieval stonework.

A micro-thin layer of fat, derived from olive oil, could be used to form a waterproof layer over the limestone, after researchers from Cardiff University, working at the Minster, discovered the technique.

Dr Karen Wilson, one of the chemists working on the project, said iconic buildings like the Minster are suffering from the effects of acid rain.

She said: “York Minster is one of the largest Gothic cathedrals in Northern Europe, and has occupied the same site since 600 AD.

“Along with many other historic structures of its era, York Minster is eroding at a noticeable rate, and periodic renovations and attempted restoration efforts using the best materials available at the time have, in some cases, accelerated the decay.”

According to the Welsh research team, the technique works by applying a layer of fatty acids to the Minster’s magnesian limestone, which then forms a hydrophobic – or waterproof – coating which can stop rain getting in but is porous enough to let salts and moisture escape.

Dr Wilson said: “You only have to look at Cardiff’s Cathays Park civic centre and Cardiff University’s own Main Building to see the number of historic limestone buildings we have here in Wales.

“Wales, like many other parts of the UK, also has an abundance of beautiful limestone churches, cathedrals and other landmark buildings.

“We hope our work at York Minister will offer a new treatment to preserve limestone buildings across Wales already suffering from the effects of erosion.”

The research, which is funded through the Science and Heritage Programme and published in the journal Scientific Reports, could now be used to help conserve other historic limestone buildings around the world.