Removal of adhesives and coatings on iron artifacts using pulsed TEA CO 2 and Nd:YAG lasers

Abstract

Selective and precise removal of surface coatings and contaminants can be achieved using lasers with a suitable wavelength. In this study pulsed TEA CO2- and Nd:YAG- lasers have been used to remove old adhesive and coatings from iron artifacts. This laser cleaning technique can enable extremely precise removal of old coating layers without damaging the underlying metal. Cleaning test on different samples using an Nd:YAG-laser with wavelengths of 1,064 nm, 532 nm and a TEA CO2-laser with 10,600 nm have been carried out. Trial sample were treated with different kinds of adhesive and coatings used in metal conservation and then cleaned using the three lasers. The results were compared with a conventional technique, micro blasting. Comparison of the laser cleaned surfaces was performed by optical microscopy and Raman-spectroscopy. The comparative study showed that the best results were achieved with the TEA CO2 laser, with the coatings being removed entirely without damage to the substrate. The original surface of the substrate was preserved and any re-deposited particles could be removed easily using a scalpel or brush after the laser radiation treatment.