Ancient Egyptian tombs are priceless, and conserving them is a challenge to conservators. For the first time ever, researchers have used laser light to remove the accumulated dirt of millennia. The setting was the tomb of a high-ranking official not far from the Valley of the Kings.
If only Neferhotep could see it: 3 300 years after his death, a researcher enters his tomb, directs a beam of light at the wall, and the accumulated dirt of millennia comes off with no trouble at all! 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 an Egyptian tomb. Adorned with wall paintings, stone sculptures and reliefs, the tomb was once that of the senior scribe Neferhotep, who served in the temple of the god Amun. "The paintings on the walls are immeasurably valuable, for they tell us a great deal about the life of a high-ranking official", explains conservator Birte Graue. In this project sponsored by the Gerda-Henkel-Stiftung, 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 the physicist Michael Panzner.
Armed with a mobile laser supplied by Clean-Lasersysteme GmbH, the Fraunhofer researcher went up 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", explains 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," says 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 result is impressive: "The technology is highly suitable for removing dirt in ancient Egyptian tombs", Christina Verbeek sums up. "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."
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