SOLARIZATION BEHAVIOUR OF MANGANESE-CONTAINING GLASS: AN EXPERIMENTAL AND ANALYTICAL STUDY

This paper is an initiative study of the solarization phenomenon of archaeological glass that until now has been recorded, but not extensively studied. It also aims to reveal the fact concerning this phenomenon as a photochemical process that affects the spectral and optical properties of ancient glass. Many solarized or purpled glasses found at Barsinia archaeological site in Jordan were collected and analyzed using atomic absorption spectroscopy (AAS) technique to identify the elemental composition of these glasses. Furthermore, many pieces of decolorized or colourless glasses containing reduced manganese were exposed to a concentrated ultraviolet (UV) radiation in accelerated weathering chamber for long times. A preliminary examination by light transmission microscopy and using double beam spectral photometers allowed determination of the changes in optical properties (transmittance and colour) of selected glasses. However, it is the goal of this paper to show that solarization becomes more than an aesthetic problem when it occurs on glass components of an optical system. Solarization may also permanently degrade a material's physical or mechanical properties.