A Preliminary Study into the Suitability of Femtosecond Lasers For the Removal of Adhesive from Canvas Paintings

Abstract

The numerous attempts to use lasers in different fields of conservation reflect awareness of their potential as non-contact tools which may be tailored to specific cleaning problems. Ultrashort laser pulses, in the order of pico- and femtoseconds have been used for precision ablation of biological tissue and have been shown to eliminate collateral damage normally caused by thermal diffusion of the laser pulse. Thermal damage and photochemical changes have both been reported as by-products of laser cleaning experiments with Excimer lasers and thus femtosecond lasers potentially offer significance benefits in this application. In the work reported here a specific problem within painting conservation has been addressed to assess the suitability of femtosecond lasers; namely the removal of glue-paste adhesive from the reverse side of a painting on canvas. This study is based on a collaborative project between the Conservation Departments of the Courtauld Institute of Art, the Tate Gallery, and the Femtosecond Optics Group at Imperial College of Science, Technology and Medicine. In this study 10ps, 830nm pulses derived from a Ti:Sapphire laser were used to ablate marks with a diameter of 5 square m and a depth of 10 square m in a glue-paste layer on canvas. The surface characteristics of the ablation marks on glue-paste, canvas and priming were investigated using microscopy. Ablation occurred irrespective of material type and no thermal damage was observed.