Olive Oil Coating Protects Limestone Buildings

Historic buildings made of limestone can now be coated so that acid rain and airborne pollutants have much less effect but, at the same time, the structures can still ‘breathe.'

Developed in the UK, the specialised limestone building coating was created in response to the deteriorating condition of historic buildings like the famous York Minster, with weathering and other factors all having taken their toll over the years.

It was produced by scientists at Cardiff University - working alongside representatives from Diamond Light Source and the University of Iowa - and it blends olive oil-based fatty acids with fluorinated substances.

Limestone Building Coating

York Minster was one of the structures used to test out this limestone building coating's properties. One of Northern Europe's largest cathedrals, it's many centuries old.

'In common with many historic structures of its era, the exterior stonework of York Minster...which has occupied the same site in England since 600 AD, has suffered extensive weathering by atmospheric pollutants', explain Cardiff University's limestone preservation research team.

Specifically, over time, York Minster has been subjected to sulphur dioxide, acid rain and other damaging substances, greatly eroding it. Exacerbating the situation, previous restoration processes have, in some instances, only made it deteriorate at a faster rate.

Olive Oil Limestone Treatment

These qualities made York Minster a perfect choice for this olive oil limestone treatment and, from here on in, the researchers suggests there's many other viable candidates that could be protected in the same way.

Significantly, the anti-pollution coating doesn't block microstructures and, with salt and mould being discouraged from building up on the surface, the stones aren't stopped from ‘breathing'.

"This paper demonstrates that buildings and statues made out of limestone can be protected from degradation by atmospheric corrosion, such as corrosion due to pollutant molecules and particulate matter in air, by applying a thin, one-layer coating of a hydrophobic coating", said the University of Iowa's Professor Vicki Grassian. "We showed in particular that the degradation of limestone from reaction with sulphur dioxide and sulphate particles could be minimized with an application of this coating."