Glass was often the preferred material for storing expensive oils, perfumes and medicines in antiquity because it was not porous. By the 1st century AD, the technique of glassblowing had revolutionised the art of glassmaking, allowing for the vessels to be produced for a range of different purposes. Glass vessels are found frequently at Hellenistic and Roman sites, especially in cemeteries, and the liquids that filled them would have been gathered from all corners of the expansive Roman Empire. A large part of ancient glassworks was designed for tableware use, in particular for carrying and serving water and wine at banquets. Jugs, one of the most frequently used containers, were created in various shapes and sizes.
The iridescence on ancient Roman glass was unintentional, and was caused by weathering on its surface. The extent to which a glass object weathers depends mainly on the burial conditions; however, the humidity, heat, and type of soil in which the glass was buried also all affect its preservation.
To find out more about Roman glass please see our relevant blog post: Collecting Roman Glass and Ancient Roman Glass.