Laser for tomb raiders

A Fraunhofer physicist is using an adjustable mobile laser to remove the accumulated dirt of millennia from the walls of an ancient Egyptian tomb.

Dr. Michael Panzner of the Fraunhofer Institute for Material and Beam Technology IWS in Dresden is the first scientist to use a laser for cleaning Egyptian antiquities.

Adorned with wall paintings, stone sculptures and reliefs, his first cleansing project is the tomb of the senior scribe Neferhotep, who served in the temple of the god Amun and died 3,300 years ago.

“The paintings on the walls are immeasurably valuable, for they tell us a great deal about the life of a high-ranking official,” said conservator Birte Graue. In this project sponsored by the Gerda Henkel Foundation, she and her colleagues Susanne Brinkmann and Christina Verbeek are seeking new techniques for cleaning the surfaces of ancient Egyptian tombs. The team is supported by Panzner.

Armed with a mobile laser supplied by Clean-Lasersysteme, the Fraunhofer researcher climbed into Neferhotep’s burial chamber and started his pioneering work on a narrow strip of wall just a few millimeters wide.

“Cleaning art monuments with laser light is a challenge in many ways,” said Panzner. “Because they are unique, they must on no account be damaged. In addition to this, every subsurface, be it plaster, mortar or stone, has specific physical properties and reacts to the laser light accordingly.”

The art is to adjust the frequency, pulse energy and pulse duration in such a way that the dirt is removed while conserving the paint and the subsurface. “We approached these problems with great caution,” said Panzner.

He started off by treating the test areas on the wall of the burial chamber with laser parameters that applied only a very low energy charge to the surface. After each trial run, he and the conservators examined the result through a microscope. Then they gradually modified the parameters until the ideal settings for damage-free cleaning had been found.

The conservators were impressed with the results. “The technology is highly suitable for removing dirt in ancient Egyptian tombs”, said Verbeek. “If you know what the laser can do, and what its strengths and weaknesses are, it is an excellent supplement to the usual mechanical and chemical conservation methods.”