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New laser technology for painting restoration

Revolutionary non-contact cleaning method to be unveiled this month at Liverpool’s laser conservation conference

A new non-contact method of cleaning paintings is to be presented at LACONA II, the second International Conference on Lasers in the Conservation of Artworks, which takes place in Liverpool, 23-25 April. Invented by Dutch painting restorer Milko Den Leeuw with Professor C. Fotakis of FORTH, the Greek Foundation for Research and Technology, the method combines laser technology with computer analysis to remove dirt, atmospheric contaminants and overpainting from a painting’s surface.

Although lasers have been used to restore artworks for thirty years, it has mainly been for sculptures (see The Art Newspaper No.46, March 1995, p.19). By combining the laser with computer diagnostic capabilities, Den Leeuw and Fotakis have created the first restoration method capable of monitoring the condition of a painting during the restoration process.

Den Leeuw and his associates are now at work on a pilot project in the Netherlands where a laser station is under construction at the University of Twente to be used in cleaning a seventeenth-century ceiling painting recently discovered in an Amsterdam canal house.

The method boasts significant advantages over traditional methods: it is non-invasive, easily controlled, and appears capable of removing foreign substances which neither scalpels nor chemicals are able to penetrate. Consequently, paintings previously considered uncleanable may be candidates for laser treatment. Moreover, the “cleaning threshold”, the point at which a restorer must decide to stop cleaning in order to reduce risk to the work, diminishes virtually to zero using Den Leeuw’s method. The laser removes surface dirt, yellowed varnish, overpainting, even touch-ups by previous restoration, to within one micron of the painting’s surface. It leaves a layer that, although invisible to the naked eye, protects the original art work.

Explaining the history of the project, which has received official recognition from the European Union for environmental safety because of its potential to reduce the use of chemicals in the restoration process, Den Leeuw recalls, “About eighteen months ago, I was asked to advise on a seventeenth-century Allegory of Amsterdam, done in oils on oak panel, that had been discovered under a nineteenth-century overpainting at the Kattenkabinet museum in Amsterdam.

By the time I became involved, two thirds of the overpainting had been removed by Russian restorers using scalpels. But they found it impossible to remove the central section.”

After laboratory analysis, Den Leeuw identified an inert silicon layer that was causing the problem. Discussions with his team at the Atelier for Restoration and Research of Paintings led to the idea that the surface could be removed by laser.

Den Leeuw learned of the work being conducted by Dr Fotakis at FORTH to clean Greek icons using a computer control system and went to visit his lab in Crete. With the help of FORTH’s laser expert, Dr Vassilis Zafiropulos, Den Leeuw conducted tests using a laboratory prototype of the laser cleaning station there. Inspired by his findings, he teamed up with scientists, physicists and art historians at the Universities of Amsterdam and Twente to develop a state-of-the-art laser instrument, known as SOLON. Corporations such as KODAK, Philips and LAMDA Physics have donated equipment for the pilot project.

The prototype station now being built will be “about the size of a bed”, according to Den Leeuw, and is being constructed at a cost of DFl. 1 million (£333,000; $533,000). Most of this funding has come from the European Union, with additional support from the Dutch government and private foundations. Den Leeuw was quick to note, however, that the costs of the prototype model are significantly higher than those for future models.

SOLON is not the only laser system applied to conservation, but Den Leeuw believes his system is the most advanced. “Many of those involved in the application of laser technology conservation have failed to appreciate the importance of ensuring a synergy between restorers, art historians, and, of course, chemists,” he observed. “Moreover, little attention has been paid to developing the diagnostics that would enable us to control the process of returning an object to its original condition, as SOLON does,” he said.