Laser stain removal of fungus-induced stains on paper-based cultural relics
IRG/WP 07-40389
Tsang-Chyi Shiah, Han Chien Lin
Laser techniques has been developed and applied in commercial use for 40 years, but it has not been used successfully to remove stains from paper-based cultural relics . The purpose of this study was to investigate the paper cleaning by using a technique of Nd-YAG laser. Artificial stained papers were inoculated with fungi and then were treated at different laser cleaning parameters, in order to find out the best treating conditions.
Experimental results showed that 1064 nm of laser wavelength obtained a superior cleaning effect, especially for the black and /or darken fungal stains. It also found that no significant loss was detected on the brightness and the zero span strength of laser treated paper specimens. The Nd-YAG laser treated paper specimens exhibited that the superior brightness improvements in the order of 10Hz with 10 pulses; 10Hz with 5 pulses; 10Hz with 1 puls. After being removal fungal stains from the surface of paper specimens, the IR absorbance spectra represented that the special function group for either the amino acid of fungi or the carbonyl group at 1550 cm-1 and 1650 cm-1, were disappeared or decreased . It is suggested that the Nd-YAG laser can be a viable alternative conservation medium for paper-based of artifacts and archives.
Keywords: Laser cleaning, Nd:YAG laser, Mold stains, Paper-based cultural relics.