Digging Glass: A Day in the Glass Lab

June 29th found me, as it usually does, doing archaeology.  Some years I’m excavating, some years I am lecturing to groups who are visiting sites like the ones I’ve excavated, and some years, like this one, I am working away on the publication of finds from all those years of excavating.

Glass is a beautiful, seductive material and a rich source of evidence about technical and aesthetic aspects of a culture and about the complex processes of exchange and influence between cultures.  Glass — luxurious, expensive, and resource intensive — reflects the decision-making of the elites and their sense of style. The production of glass is a fundamental technology based on complex technical knowledge and specialized skill. Glass, discovered by accident, grew to transform the environment of daily life by brightening tables and structures. The story of the coming of age of glass is one of the fascinating stories in the history of technology. One you should check into.

I am currently working on the glass from three sites:  Aila and Humaya in Jordan, and Gordion in Turkey.  The glass recovered from these three sites covers the gamut of glass forming technologies (molded, core-formed, mosaic, blown) and ancient periods of production (Iron Age through early Islamic).  So working on archaeological glass asks for a dedication to the material itself in all its life phases and permutations.  Ever since I worked at the Jamestown Glasshouse during my undergraduate years, it’s been glass for me just as it’s coins or bones or pottery for someone else.

Today, on the Day of Archaeology, it’s Roman glass from Gordion, the capital of the ancient kingdom of Phrygia.  I am beginning to write up the chapter on Roman glass for a final report.

Gordion had an interesting Roman period, one until recently mostly overlooked, and has produced interesting Roman glass that reveals periods of economic prosperity, a taste for luxury glass tablewares, and information about Gordion’s connections to the outer world in the period.

For today, a closer look at a heavily weathered fragmentary mosaic bowl.

mosaic bowl fragments

Heavily weathered fragments of mosaic bowl in new container.

As with the study of other artifact, the study of this glass has several stages.  Because we are not permitted to remove the glass from Turkey, I have carefully examined, measured, described, and drawn each artifact in the depots at the excavation house near Gordion.  Here in my lab at Bucknell University this summer I am working from my drawings, notes, and from photographs I have taken in Turkey (some of which are below).

This fragmentary bowl was excavated in 1951 and had received relatively little (no?) attention over the years.  Several years ago we moved the fragments from a candy box with tissue paper padding into a beautifully designed container created by Ariel O’Connor, a Gordion conservation intern.  It has been a puzzling vessel for me because of the heavy weathering, but seemed clearly to be a mosaic bowl of some sort. I have worked with conservators on site to remove some of the weathering layers to see what lay below.  What you see in the following photos is what we found.

Cleaned fragment.

Cleaned fragment with color scheme of mosaic strips visible (back lit).

Great excitement as we uncover gold!

Cleaned fragment with gold band visible in sunlight.

Fragment with gold band (back lit).

Quite a difference from those gray, filmy pieces in the first picture!

Here’s a photo of  part of the rim of the bowl:

Cleaned fragment of rim (back lit).


Today, in my library full of studies of excavated glass and museum collections, I have been trying to figure out the technique, color scheme, and date of the vessel.  I am also trying to locate comparable excavated pieces or pieces in collections that will give me hints to the origin and date.

A final entry on this piece in my field notebook says the fragments appear to show that the vessel was fashioned from tooled strips of canes with a repeating sequence of turquoise blue, yellow edged in purple, opaque white edged in dark blue, and colorless encasing shattered gold leaf.

A wonderful aspect of my job is spending a pleasant hour or so leafing through likely museum catalogues and that thrill of discovery when I find, just now, what I was looking for – a parallel in profile, technique, and color scheme, in a favorite publication – David Grose’s catalogue of early ancient glass in the Toledo Museum of Art (1989).

And the answer is:  The vessel is very likely a gold-band mosaic bowl of the early to mid-first century BCE.  The profile is that of a broad shallow bowl with an upright rim with a narrow rounded edge. It was likely assembled in sections from tooled, fused strips, molded, then rotary polished.  It is one of two bowls (some of the fragments are definitely from a second bowl).

New problem(!):  The bowl appears to come from a securely dated context – a destruction level – that’s a century earlier than that.  Hmm.  Well, this is how we make progress.   Stay tuned for the final publication!

Michael Marshall: Assessing Small Finds From Roman London Part 2

So the many, many boxes of nails, thank god, are now a distant memory. At the assessment stage we only do a fairly coarse quantification in order to determine the potential of the material for further work. This sometimes just involves weighing and counting the fragments but when preservation is good enough some other data can be collected such as number of complete nails from each context (divided into broad size categories), minimum number of nails and comments on particularly distinctive styles or features. The point of this isn’t to write a definitive account of the use of nails on the site but to assess their potential for further analysis, decide what role they will play in the final publication and how they can help us to address research questions.

Unfortunately, it’s probably not worth doing much more work on the Southwark nails as they are in terrible condition. Most are completely encrusted or incomplete and the assemblage is quite small with a maximum of c. 15 fragments from any given context making any inferences of limited value.

Much more exciting this afternoon is the Roman glass and glass working waste which will definitely feature in the final publication. As mentioned briefly in my previous post, this seems to be the first Roman glass-working evidence from this side of the river. The types of waste include ‘moils’ (glass from the end of the blowing iron left behind when you crack the vessel off) as well as a variety of melted, fused and runny lumps.  Threads, pulls and trails etc derive from more detailed manipulation of glass during decoration or the addition of handles etc.

Glass working waste from Basinghall, London: Threads and Nails( (c) Andy Chopping, MOLA)

The assemblage is relatively small so far with only about 25 moils worth of fragments accounted for, each of which equates to a vessel manufactured onsite. This estimate is based on EME (estimated moil equivalent) a technique lifted from pottery studies (EVEs) which is calculated by measuring the proportion of the moil diameter present in each fragment. Of course many more vessels could have been made and the moils recycled or not recovered. Vessels were being made from both naturally coloured blue-green glass and amber coloured glass.

Glass working waste from Basinghall, London: Moils ( (c) Andy Chopping, MOLA)

The general range of waste types is not dissimilar to those found at the much larger glass-working dumps at Guildhall Yard and Basinghall Street across the river in Londinium (see pictures below) and, like those dumps, the waste was found alongside lots of broken vessel and window glass intended for recycling. Raw Roman glass was brought all the way from the Mediterranean so recycling this ‘cullet’ made good economic sense. Identifiable fragments of bottles, beakers, jugs and jars from amongst the smashed up vessels suggest a probable date in the early to mid 2nd century AD for the glass working.

If glass working interests you check out this website and a great little book called Glass workers of Roman London by John Shepherd and my colleague Angela Wardle, which provides an interim popular account of their work on the Basinghall assemblage and the techniques of glass making.  Their work on the final monograph is nearing completion, but luckily the new evidence from Southwark should still just about make it into the gazetteer of glass-working sites included in the text, and contribute to their discussion of the organisation of the industry.

That’s enough from me. I don’t have time to tell you about the lamps, finger rings, combs, figurines, crucibles, hairpins, querns, toilet instruments, tools or the large and interesting assemblage of glass vessels I have already recorded from the site. Unfortunately, I can’t even tell you about the cosmetic mortar or the blue blobbed glass beaker, probably an import from the Rhineland, which I recorded yesterday. The whole point of the assessment stage is so we can get our head around what we’ve got, and how best to study and publish it, so if you want to know more you’ll need to hang about. This is certainly shaping up to be an interesting site and I’ve already spent too long waffling here and not enough time doing my glass data entry.

Now if you’ll excuse me, I need to get back and finish this context before the end of the day, so I can get to the pub on time.


Day of Archaeology – LAARC Lottery Part 3 (Registered Finds)

Here are the results from our registered finds shelf lottery

Shelf seven (suggested by Pat Hadley – thanks Pat) of our Registered finds section of the Archive is the start of a sequence of finds that were excavated before professional archaeology became existed inLondon, during the very early 1970s. At this time theMuseumofLondon’s forbearer – the Guildhall Museum– was undertaking excavations across the city. This object – a classic Roman oil lamp – was excavated on Gracechurch street in 1969.

Roman Lamp from GM69 site

Roman Lamp from GM69 site – and shelf number 7

This Roman lamp is known as a picture lamp, as the central ‘discus’ is decorated. It may be a Loeschecke (1919) Type IV, although difficult to tell as types are usually distinguished by the nozzle, which in this case is broken. It probably dates to the C1st AD and in particular the Boudican revolt as it was discovered in association with a major burnt strata with other C1st pottery.

A very similar lamp has also been discovered on a recent Archive volunteer project – VIP9 – although not in such a good state of preservation! Closer comparison may reveal if it was made from the same two-piece mould, as these objects were mass produced.

Shelf 342 (tweeted by our very own Adam Corsini while on holiday in Sardinia) of our Registered finds stores material from the 1980s, a point in time when archaeology withinLondonhad become highly professionalised – having a major impact on how we eventually archive material and records from excavation.

Our second lucky winner(s) are  fragmentary pieces of medieval window glass. Excavated on the site of the Royal Mint in 1986, this glass may have formed part of the medieval Abbey or Chapter House. By the C16th window glass such as this would have been found more commonly in secular buildings as opposed to religious buildings. Although extremely aesthetic, the array of colours this glass has produced are not intentional – this is actually the glass decomposing, or delaminating, as a result of being buried in the ground for hundreds of years.

Fragments of medieval stained glass from MIN86

Fragments of medieval stained glass from MIN86, and shelf 342

Next it’s our Metal artefacts – these objects are stored separately. A dehumidified store, sealed boxes and silica gel help us maintain these objects to a high degree of preservation as they’d slowly degrade in normal room conditions. Tweet using #dayofarch or #LAARC, or message us below, a number between 1 and 628 to discover, completely at random, what that shelf holds…


Michael Marshall: Assessing Small Finds from Roman London

Like any job in archaeology, working with small finds can be a bit of a mixed bag. For every box opened to reveal shiny ‘treasure’ there are countless others containing more prosaic yet interesting finds which are indicative of everyday life and activities in the past. These are really the ‘best bit’ of any assemblage but more numerous still on many urban sites are boxes full of highly fragmentary and corroded ‘dross’. Some of this is completely unidentifiable, fairly undiagnostic (such as fragments of iron sheet or wire) or else tantalisingly close to being a recognisable object leading to some speculative flicking through likely find’s books or trips around the office to bother colleagues.

Today I am working on a post-excavation assessment report for an interesting Roman site in Southwark and it is no exception. This morning I’ll be dealing with some more of the most corroded horrible bulk nails it’s ever been my misfortune to handle (don’t expect any terribly enlightening updates about these) but this afternoon I have some more nice Roman glass to round off the week so stick with me. There are lovely glass vessels in this assemblage and some evidence for glass working – probably the first evidence of this sort from south of the river.

In the meantime I’m off to grab some gloves and some more boxes of nails. At least it’s a bit cooler today. I grew up in Scotland and so anything above about 24°C is a bit on the warm side for me and it was horrible yesterday when it topped 31 degrees in the office. I was wearing gloves and a dust mask and had to close the windows and turn off the fan in my section of the office to stop all the dust, rust and muck from the nails choking the osteologists and finds specialists I share a room with. For the present here’s a photo of my rather generic desk in that room to contrast with all the lovely site photos that I’m seeing appearing on the website already. This is ‘where the magic happens’… or something like that. The sharp-eyed will notice the awesome (free and pretty accurate) BBC prehistory timeline above my computer.

Treasure ahoy!

Where the magic happens