An end in sightFebruary 22, 2008 Roman glass
I have now recorded over 1500 nearly complete moils and fragments of moil and I am beginning to count moils instead of sheep at night! John has sorted and recorded a similar number, so the end is in sight and we hope to finish this stage of the project by the end of February. Then we will start on the challenging task of analysing the data and seeing what it all means.
I have had a few questions about Roman glass this week. Tom wanted to know how it survives in the ground for so long without breaking. Well of course most of the glass we deal with is broken, – it is usually rubbish, vessels which have been broken and thrown away, or put into ‘bottle banks’ for recycling, but the glass itself survives so well because it was very stable.
The main ingredient of Roman glass was silica, in the form of sand. Soda was added to this as a flux, to reduce the melting temperature of the sand and calcium (lime) was added to stabilise the mixture. The whole lot was heated in a furnace, in crucibles, or in a large tank, until it melted and fused together to form raw glass, which in its natural form has a greenish blue colour, due to impurities (iron oxide) in the sand. Glass was made first in the eastern Mediterranean region, where all the raw ingredients were in plentiful supply, and was exported in large chunks to be reworked into vessels.
Glass was used for many purposes, and while it was probably always quite expensive, there is evidence throughout the empire for a massive increase in the use of glass vessels in everyday life after the invention of glass blowing. We can certainly see this in London, where glass was used at table for serving vessels and for drinking cups. Bottles and flasks were used for transporting all sorts of liquids, – wine, oil and water and many different foods. Some of our finest glass vessels come from burials, where they were placed intact, containing food, drink or perfumes for the deceased, with no intention of recovery. These bottles never found their way into the recycling collections.
Glass was also used for windows, to make tesserae for the most elaborate floor and wall mosaics, for stirring rods, used with cosmetics and unguents, and for gaming counters.