Monks' Secret: Asbestos Lurking Beneath Byzantine Wall Paintings

Hundreds of years before asbestos became ubiquitous in the construction industry, Byzantine monks used the fibrous material in plaster coatings underlying their wall paintings during the late 1100s, new research shows.

Asbestos is a type of natural, rock-forming mineral known for its ability to separate into long, flexible fibers. It has long been thought that asbestos fibers, which are corrosion- and combustion-resistant, were first integrated into such things as plaster, finish coatings and floors after the Industrial Revolution.

But while investigating the 12th-century paintings in the Byzantine monastery Enkleistra of St. Neophytos in Cyprus, UCLA researchers discovered the magnesium silicate mineral, chrysotile (white asbestos), in the finish coating of the plaster underneath a portion of a wall painting. The chrysotile provided a smooth layer with a mirrorlike surface for the painting. [See Photos of the Byzantine Monastery and 12th-Century Paintings]

Image: UCLA archaeologist Ioanna Kakoulli examines a painting in the monastery under UV light
The researchers analyzed some of the paintings on site using various techniques, including infrared, ultraviolet and X-ray fluorescence imaging. Here, UCLA archaeologist Ioanna Kakoulli examines a painting in the monastery under UV light. Ioanna Kakoulli, UCLA via Live Science

"[The monks] probably wanted to give more shine and different properties to this layer," said UCLA archaeologist Ioanna Kakoulli, lead author of the new study, published online last month in the Journal of Archaeological Science. "It definitely wasn't a casual decision — they must have understood the properties of the material."

Though all six asbestos minerals are now known to be carcinogenic, people have taken advantage of the fibrous materials' unique properties for millennia. About 4,500 years ago, artisans mixed asbestos minerals with clay to produce stronger pottery. And 2,000 years ago, asbestos fibers were woven into textiles to make fireproof napkins (that were "washed" by tossing them into fire), or to make a special fabric that could separate human ashes from funeral pyre material during cremations, Kakoulli said. "It was considered to have magical powers," she told Live Science.

In the late 19th century, people used asbestos in industrial products — including cements, wall plasters, joint (drywall) compounds, fire-retardant coatings and roofing, among other things — to increase their durability, insulation and weathering protection.

Given this history, Kakoulli and her colleagues weren't expecting to find asbestos on the walls of Enkleistra of St. Neophytos. They initially set out to see if there was any change in the materials used to create the monastery's numerous wall paintings over time.

Two online reports provide further details on the project.

— Joseph Castro, Live Science

This is a condensed version of a report from Live Science. Read the full report. Follow Joseph Castro on Twitter. Follow us @livescience, Facebook & Google+.