Removal of adhesives and coatings from iron artifacts using pulsed TEA CO_2- and Nd:YAG-lasers

摘要

Selective and precise removal of surface coatings and contaminants can be achieved using lasers with a suitable wavelength. In this study pulsed TEA CO_2- and Nd:YAG-lasers have been used to remove old adhesives and coatings from iron artifacts. This laser cleaning technique can enable extremely precise removal of old coating layers without damaging the underlying metal. Cleaning tests on different samples using an Nd:YAG-laser with wavelengths of 1,064 nm, 532 nm and a TEA CO_2-laser with 10,600 nm have been carried out. Trial samples were treated with different kinds of adhesives 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 CO_2 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.