Roman Glass Research Project

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.

Another long gap between postings, due to being entirely swamped with work. At the beginning of February I took time off to do some lecturing on Roman glass to students from the University of London – a chance to talk about the history of glass working and to show pictures of some very fine vessels. They also had a chance to handle some of the more mundane fragments.

Since then John and I have settled down in earnest to the problem of recording the moils (those little cylinders of glass left on the blowing iron when a vessel was removed). Considering that every one of these little cylinders of glass represents a blown vessel, it is important to work out how many complete moils there may have been. The differences in size and shape might also indicate different techniques, perhaps the idiosyncrasies of individual glass blowers. For example, some moils are very long and slender, while others, cut off very close to the blowing iron, are extremely short. Now this might be because they are from different types of vessel, but it might also be the way in which particular craftsman worked.

On our best examples it is possible to see a mark left by the edge of the blowing iron, which gives us its diameter and we have decided to divide the moils into groups based on the probable diameter of the iron. We have then subdivided these groups according to particular features of the moil – length, thickness, shape (cylindrical or tapering) and so on. All these basic measurements are being recorded on a database, together with the weight of the fragment. We are also recording how much of a complete moil each fragment represents, using an adaptation of a method originally devised for pottery studies (a complete moil is 100%).

All these measurements take some time, but we have to ensure that we are recording as much as possible, as we will not get another chance! Of course many of the fragments, although identifiable as moils, are so incomplete that we cannot take any measurements, but I reckon, that we still have several thousand moils to classify and record individually. I have probably done about 750 so far ……

If anyone (is there anyone out there?) has any burning questions about the project – or anything else about Roman glass, do post a comment, and I shall do my best to answer it – in between moils of course!