Feasibility of ultrafast picosecond laser cleaning of soiling on historical leather buckles

Abstract

The aim of the research is to present a system recently developed and used for automated cleaning of artworks and to examine the suitability of using this ultrafast and precise computed-scanning picosecond laser (1064nm) with a repetition rate of 10kHz and a temporal pulse length of 10ps for the removal of soiling from leather buckles without damaging the leather substrate. Preliminary tests will be performed with the model artificially aged vegetable tanned samples to determine the leather damage threshold fluence and the soiling ablation threshold fluence before using a laser for the removal of the soiling from a historical leather buckle. As laser cleaning requires a physical parameterization for optimization of cleaning accompanied with an assessment of the morphological and chemical changes of leather, an investigations were performed to determine the leather damage and ablation threshold fluences of artificially aged and historical vegetable tanned leather using a number of analytical techniques including differential scanning calorimetry, optical microscopy, scanning electronic microscope with energy dispersive X-ray analysis, colorimetry and Fourier transform infrared spectroscopy have been used. Following optimization trials of the picosecond laser cleaning parameters on model leather samples, satisfactory removal of the soiling over the historical leather surface is achieved. Graphical abstract The graphical abstract shows the selected metal buckels covered with leather for this study (fig. 1), the chemical composition of the soiling (Fig. 2) and laser cleaning tests for removal of soiling over the vegetable tanned leather (figs. 3 and 6).