THz spectroscopy for art conservation science

The scientific analysis is an important process in art conservation for collecting information of materials used in original work as well as in previous conservation processes. Recently terahertz spectroscopy has progressed rapidly and it is expected that its spectra are more material specific compared with those of mid-infrared regions, so that it can give useful information to identify materials used in art. We have observed spectra of various historical and modern pigments and binders. Almost all pigments in more than 100 specimens have fingerprint peaks, and binders also have specific spectra. Thus, THz spectroscopy can distinguish the pigments which have the same colour, and can distinguish binders used with the same pigment. THz spectroscopy can also identify the transparent body pigment in colour pigments. It should contribute to art conservation as a new non-invasive examination method. Moreover, the first- ever THz spectra database of art materials should contribute to the various research fields such as the food and pharmaceutical industries because art materials are also commonly used.