The excavation of several thousand life-size terracotta warriors in China has fascinated the world ever since the army was first uncovered by archaeologists in 1974. Buried in moist ground, these clay figures have remained mostly intact for over 2000 years. As soon as they are exposed to air, however, the paint on the warriors curls up and breaks into small flakes. Conservators are deeply worried.
For many years, the preservation of our cultural heritage was mainly the domain of the humanities. Lately, however, science has played an increasing role in the analysis, conservation and restoration of historical objects. For such unique and delicate specimens, analytical techniques must be non-invasive. Moreover, all the restorative procedures should be well controlled and carried out with the utmost concern for the invaluable historical object in question.
In the November issue of Physics World, Klaus Hinsch and Gerd Gülker of Carl von Ossietzky University, Germany, explain how lasers are providing a powerful and versatile set of tools for surveying and analysing historical treasures, including frescoes, painted icons and figures.