Trials have begun at York Minster cathedral, where ancient masonry made from limestone is at risk.
Laboratory tests have shown a “cheap and simple” coating of the oil, more commonly associated with salad dressing, repels water and the sulphurous pollutants which cause limestone buildings to turn black and crumble.
It’s hoped the compound could save tens of millions of pounds in restorations costs for some of our most treasured buildings, monuments and statues.
In the past, solutions made from egg white and egg wash to linseed oil and vinegar have been used to try to stem the damage caused by environmental pollution.
But these coatings have failed because they have sealed the stones too tightly and not allowed them to “breathe”, When the coating cracks or fails, mould and fungus grows inside the seal, causing more damage.
Since the industrial revolution they have been having problems with decay
However, the new coating made of oleic acid, which is found in many plant sources including olive oil, appears to work much better.
It has been developed by scientists Dr Karen Wilson and Professor Adam Lee from the School of Chemistry at Cardiff University, with US scientists at Iowa University.
Professor Lee, whose findings appear in online journal Scientific Reports, said: “Like many buildings of the time York Minster is built essentially of magnesian limestone and acid rain does not react very well with that.
“Since the industrial revolution they have been having problems with decay.
“We tried to develop some very cheap and simple coating methods in using conventionally occurring fatty acids like oleic acid, which is a common component of olive oil. This would not be toxic and could be applied across a huge building. It is a very cheap, viable and non-toxic coating.”
The ingredient is mixed with a Teflon-like substance to repel water, a key factor in stopping decay.
Prof Lee added: “We haven’t gone up York Minster yet with paint brushes because they are very protective of the stonework, but we have treated actual stones and it is looking very promising.
York Minster, built between 1220 and 1470, is recognised as one of the world’s most magnificent cathedrals.