Dry ice blasting for the conservation cleaning of metals

This research was carried out to assess the feasibility of dry ice blasting as a replacement for solvent cleaning for the removal of organic layers from metal cultural heritage objects. The effects of dry ice blasting on test samples of aluminium, bronze and weathering steel were studied along with its effectiveness at removing organic layers from four objects. Metal surfaces were studied in detail before and after cleaning using light microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). It was possible to remove wax layers from most of the metal samples. The removal of spray paint from aluminium was very successful, however, its removal from weathering steel proved very difficult. The gradual removal of patina/corrosion from weathering steel and bronze was possible without damaging the substrate. Results indicate that dry ice blasting is a good alternative to other air abrasive methods, such as sandblasting or walnut shell blasting.