The physical properties of Alexandrian Roman glass: Industrial optimization in the first world market

The viscosity and thermal expansion samples from a well-preserved Roman glass ingot from the late 2nd-early 3rd century Embiez-Ouest 1 shipwreck have been measured over wide temperature ranges to determine how this material was originally produced and how to preserve it now. Measurement of the viscous and volume relaxation indicate that the annealing range of this glass ranges between 750 and 780 K and exemplifies the fact that relaxation kinetics depend not only on temperature but also on the structural state of the glass. As investigated by differential scanning calorimetry, a very slow cooling rate of about 0.4 K/day has been determined from the glass originally produced, which agrees with the size of up to 20 tons of the tank furnaces dug out in the Egyptian Wâdî Natrûn area. In terms of both chemical composition and properties, Embiez Ouest 1 glass is strikingly similar to modern window glasses. Relying on abundant natron and shell-bearing siliceous sands, this early successful industrial optimization thus made mass production possible to such an extent that it gave rise to the first industrial world market. • In the Roman empire transparent glass was mass produced in the Eastern Mediterranean. • The Alexandria region was famed in this respect owing to abundant natron deposits. • Composition optimization empirically led to the eutectic of the Na 2 O-CaO-SiO 2 system. • Alexandrian and modern window glasses glasses have very similar physical properties. • Easy vitrification then made possible mass production and long-distance export.