Conserving Historic Buildings with Olive Oil

This slick solution allows limestone structures to repel water and pollutants.

By Mary Beth Griggs|Wednesday, December 11, 2013
Dan Bishop/Discover; Shutterstock

What does salad dressing have in common with building conservation? Olive oil.

Researchers led by Karen Wilson in Cardiff, Wales, discovered that oleic acid, a component of the food staple, has just the right properties to make an excellent coating to help preserve historic structures.

Some great historic buildings, such as the York Minster cathedral in England (pictured), are made from limestone, a popular material because it was cheap, plentiful and easy to build with. Unfortunately, limestone is also extremely vulnerable to pollution, especially acid rain. 

Previous attempts at creating protective coatings failed because they were too thick: They blocked pollutants, but also prevented limestone from expanding and contracting with changes in temperature, leading to structural damage. 

The new oleic acid coating is inherently hydrophobic, repelling water and any pollutants, and it allows the material to react to temperature fluctuations naturally. In the words of the researchers, it allows the stone to “breathe.” 

The oleic coating is also remarkably thin, just about a nanometer thick, allowing it to conform to even the smallest cracks and imperfections in the structure. Many conservation groups are now interested in putting this historic food supply to use protecting historic buildings.

[This article originally appeared in print as "Condiment Conservation."]

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