A technical study of opaque red glass of the Iron Age in Britain

Abstract

This opaque red glass occurs at an early date in Egypt in the decoration of glass vessels (Fossing, 1940) and other material has been found from excavations in the Near East at Nimrud, as circular cakes (Turner, 1954, 454), and at Persepolis, as a bead, a slab and a lump (Matson, 1957, 130). This ‘specialized’ glass continued to be made in Mediterranean countries down to the Roman era, and chemical analyses have been published of specimens from a number of sites including Pompeii and the Isle of Elephantine; these have been recorded by Caley (1962), who has conveniently collected many analyses previously published in various journals.As a result of the present work it is clear that there are two distinct types of opaque red glass. In the type which occurs earlier and then continues in use the colour and opacity are due to metallic copper in a colloidal state; in the type which occurs later, for a more limited period, much lead oxide is present and the colour and opacity are caused by small particles of cuprous oxide. Previous authors have not always clearly distinguished between the two types and therefore the frequent identification of an opaque red glass as a cuprous oxide type must be treated with some caution unless supported by microscopic or chemical evidence.