Evaluation of Laser Cleaning of Parchment Documents with a Q-Switched Nd:YAG Laser at 1064, 532 and 266 nm

Abstract

Laser cleaning experiments with a short-pulsed Q-switched Nd:YAG laser at 1064, 532 and 266 nm were performed on new clean parchment and on artificially dirtied samples. Samples were analysed with optical microscopy, low vacuum scanning electron microscopy, shrinkage temperature measurements and colour measurements. Results show that at 266 nm, laser cleaning seems inappropriate. Laser cleaning at 532 nm showed promising results at around 0.5 J/cm2 close to the cleaning threshold. Laser cleaning at 1064 nm resulted in a yellowish discoloration and at higher fluence levels surface damage.