The removal of bronze paint repairs from overgilded picture frames using an Erbium:YAG laser

Abstract

The removal of old repairs made using metal flake paint, commonly referred to as bronze paint, has often been difficult to achieve from gilded wood and especially from oil gilded surfaces with similar solubility parameters. Conservators at the National Trust's Knole Conservation Studio in the UK treated gilded picture frames from the Knole House collection using an energy-attenuated Fotona (Dualis XS) Erbium:YAG laser, with fluencies between 0.5 and 1.0J/cm2, pre-wetted with hydroxyl and non-hydroxyl group-containing solvents. Comparisons of the effects of cleaning using only solvents and with the laser were made, and cross-sectional and media composition analysis carried out using optical microscopy, scanning electron microscopy with energy dispersive X-ray (SEM-EDX), Raman and Fourier transform infrared (FTIR) spectroscopies.