Researchers at Princeton University’s Department of Civil and Environmental Engineering have discovered that hydroxyapatite, the primary compound found in human teeth and bones, can be used to help preserve the condition of marble, which is prone to cracking and deteriorating as a result of the effects of pollution and the weather.
"In spite of being apparently very durable, marble is actually sensitive to several deterioration processes," said visiting postdoctoral researcher Enrico Sassoni, who is also leading the investigation. "Environmental temperature variations cause the opening of cracks inside marble, and rain causes dissolution of the carved surface."
Being composed of the mineral calcite, marble naturally reacts with a phosphate salt water solution to create the hydroxyapatite. The water enters and strengthens the stone by sealing cracks from within, without affecting its color or reflectivity.
Hydroxyapatite is also non-toxic and easy to apply, adding to its advantages as a new sealant for marble. It also takes effect within 24 hours of application.
Princeton’s research team is additionally testing whether the compound is strengthened with the addition of alcohol and electric currents. With the help of sculpture restorers, a preliminary test of the hydroxyapatite’s performance is planned for the sculptures at the Palace of Versailles.