Surface study of water influence on chemical corrosion of Roman glass

Abstract

Roman glass surfaces have been studied to understand water effects on glass degradation and ionic mobility. Studied specimens mainly come from the Roman ship Iulia Felix, found on the seabed of Grado lagoon (Italy) and dated to the 2nd century AD. Many different corrosion features have been investigated including white glass, glossy glass and growth rings. A typical multilayered structure found in glass is characterised by the presence of different ions in depth profiles. Layered structure is also underlined by variations in hydration oxygen value and adventitious carbon content. Evidence of ion mobility can be found in the study of growth rings, which have metal rich centres rounded with concentric rings. The centres are characterised by the presence of antimony and titanium in their maximum oxidation state: Sb(V) and Ti(IV). The evolution can be understood according to ‘Liesegang ring’ kinetics. Data of glass surfaces have been collected using many techniques, i.e. X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and environmental scanning electron microscopy (ESEM). Several bulk techniques to characterise the specimens have been used.