Lasers for the Cleaning of Statuary: Initial Results and Potentialities

Abstract

Cleaning is one of the most difficult operations encountered in the restoration of statuary. The fact that known cleaning methods are not entirely satisfactory has stimulated continuing research into new methods and processes. A novel method is proposed for cleaning superficial black scabs or patinas from works of art in marble or other stone by means of laser radiation. Surface cleaning results with a ruby laser are reported and compared with conventional techniques. Preliminary analyses of the laser process are quite favorable and indicate improved selectivity and graduation, self-limiting encrustation removal, and remarkably rapid surface coverage. Finally, the results of cleaning tests with various laser types are presented and discussed, and possible future developments and pratical applications of this new method of cleaning statuary are presented.

Laser Cleaning as Novel Approach to Preservation of Historical Books and Documents on a Paper Basis

“…The concept of the use of laser radiation for selective removal from the surface of an optically absorbing different substance, for instance, a secondary encrustation, was first demonstrated in 1965 by Arthur Schawlow, one of the laser inventors, who evaporated selectively absorbing black pigments of printing ink from a strongly reflecting white sheet of paper [20]. Later, in 1972 John Asmus first demonstrated the laser cleaning of Cultural Heritage objects [21]. Nowadays, basic physical principles of laser cleaning are well known and described in the scientific literature (see, for instance [2,22,23]).…”

Pulsed laser cleaning: comparing science with art and cultural heritage applications

“…When the focus is on applying lasers to art and cultural heritage conservation this has tended to be reported at specialist conferences like LACONA (Lasers in the Conservation of Artworks -the seventh meeting having been held in Madrid in September 2007) and in journals like the Journal of Cultural Heritage. Lasers in conservation has a history dating from Asmus' early studies in the 1970's [33] and its wide acceptance by conservators is evidenced by its application to cleaning of some of the world's most prized artworks, such as the removal of aged varnish from Da Vinci's Mona Lisa, and the removal of pollution encrustation from Michelangelo's statue of David. Much diagnostic science has been specifically developed to underpin these conservation efforts, which must ensure that no damage occurs to these irreplaceable masterpieces.…”

Enzymatic decolorization of bacterial pigments from culturally significant marble

“…Although cleaning with water spray or air abrasion could be used, these mechanical methods may induce structural and surface damage to the marble [5]. The surface of Slide Mantra underwent multiple CB-4 biocidal detergent (Droycon Bioconcepts Inc., Regina, Saskatchewan) and steam rinse treatments during an extensive restoration in early 2007.…”