The Use of Lasers for the Removal of Shellac from Wood

The removal of shellac is a common but challenging task inthe conservation of wooden artifacts. In this work, experimentswere performed to assess the suitability of lasers forcleaning non aged shellac from pine and oak mock–ups.Optimal laser parameters were determined for preservingthe integrity of the original wooden substrate during thecleaning process. In particular, the ablation thresholds forshellac and wood were comparatively examined usingexcimer (248 nm) and Nd:YAG (1064 nm) lasers, emittingpulses of nanosecond (ns) or picosecond (ps) duration. Theinduced etching and other morphological alterations to thewood surface were assessed. The results obtained providedstrong evidence for the existence of a window of optimallaser parameters for the safe and efficient removal of shellacfrom wood, in a “self-limiting” process.