Laser Cleaning Research

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CCI Newsletter, No. 25, May 2000

Laser Cleaning Research

by Gregory Young, Senior Conservation Scientist, Conservation Processes and Materials Research

Figure 1

Meg Abraham, from the Los Angeles County Museum of Art, sets up the new Nd:YAG laser.

Advances in laser system design have steadily broadened the potential for cleaning to include organic and other inorganic substrates. Nd:YAG's are available that offer a selection of output wavelengths, including the second and third harmonics at 532 nm (green) and 355 nm (near UV) respectively, along with the standard near-infrared output at 1064 nm. Choice of wavelength, as well as energy density and pulse duration and frequency, provides the flexibility needed to establish suitable emission parameters to clean museum objects safely.

CCI has recently obtained access to a new Nd:YAG with these capabilities through a collaboration with the National Center for Preservation Technology and Training (NCPTT), United States National Park Service, Los Angeles County Museum of Art (LACMA), and Getty Conservation Institute (GCI). Initiated and funded by the NCPTT, the collaboration combines the analytical capabilities of CCI and GCI with LACMA's new laser facility in order to advance the development of Nd:YAG ablative laser cleaning. CCI is also strengthening links with the National Research Council of Canada to enhance the analytical capabilities of the collaboration.

CCI will examine the surface effects of laser-induced thermal and photomechanical action on selected cellulosic and proteinaceous materials, stone, and corroded metals. The aim is to establish the range of appropriate emission parameters for cleaning these materials without damage, and to compare the efficacy of laser cleaning and the resulting surface appearance with those of other cleaning techniques.