Objects in focus
Corroded ruin or hidden treasure?

My work as Project Conservator for the Ur Digitisation Project continues the assessment, investigation and conservation of objects held by the British Museum that were excavated at Ur (located in present-day Iraq) in the 1920s and 1930s by the archaeologist C. Leonard Woolley. You can read more about Wooley’s excavation and the project here.

One of my current tasks is to work on the metal objects.

One object in this group, a third millenium copper-alloy cauldron, discovered in the 1928–1929 excavation at Ur as part of a grave assemblage, has proved especially interesting…

In the Middle East department in the British Museum, archaeological metal objects are kept in controlled environmental conditions to ensure that corrosion is limited. Ur metal objects are usually stable although many bear the effects of long-term burial in salty, and therefore corrosive, conditions. This cauldron is a prime example!

Cauldron. The rim is detached. The wooden supports across the interior were probably added at the same time that the rim was repaired.

Cauldron. The rim is detached. The wooden supports across the interior were probably added at the same time that the rim was repaired. British Museum 1929,1017.625.

Initially it was a pitiful sight, as the on-going effects of several thousand years of burial have taken their toll. The rim was detached and in fragments and the visible parts of the metal body appeared entirely mineralised, that is, entirely corroded. Soil lined the interior in a thick layer and was clearly visible where corroded sections of the vessel wall had fallen away from the exterior. Over this soil layer, the interior of the cauldron and the underside of the exterior were lined with strips of waxed calico (coarse cotton).

Cauldron interior, showing the waxed calico lining the vessel and the fibrous putty-like material used to repair the rim (now orange-brown in colour).

Cauldron interior, showing the waxed calico lining the vessel and the fibrous putty-like material used to repair the rim (now orange-brown in colour).

The waxed calico was applied during excavation as a means to protect the object and possibly also to preserve its shape during lifting and transport. A layer of melted paraffin wax was applied over all. In more recent years, probably the 1970s, an attempt was made to secure the rim: a light fibrous putty-like material, used in conservation from the late 1960s to 1980s, is found over much of the area where the rim would have joined the body.

The cauldron initially seemed so deteriorated that it could be of value only as an example of Woolley’s excavation methods rather than as an archaeological object.

However, closer observation revealed that a large section of the rounded wall of the cauldron body appears to have survived intact, that is with only superficial corrosion apparent (the interior is hidden by the waxed calico).  The detached rims also proved to be less deteriorated than on first view. The two handles and their fixings, including large square-headed rivets, are clearly visible and in some parts well-preserved.

Cauldron rim section showing the handle fittings and rivets.

Cauldron rim section showing the handle fittings and rivets.

Although Woolley’s account of the Ur excavations gives barely a page to metal vessels such as this, he created a detailed typology of metal vessel forms. The surviving elements of the cauldron allowed it to be securely identified as Woolley’s Type 49, distinguished by its riveted handles, rounded profile and splayed rim.

Woolley’s vessel Type 49 from Woolley, C. L., Ur Excavations: The Royal Cemetery, 1934.

Woolley’s vessel Type 49.  Woolley, C. L., Ur Excavations: The Royal Cemetery, 1934.

This information made it possible to identify a series of findspots (burials), eight in total, where this cauldron-type occurred. Of these, one in particular (PG 1422) includes a cauldron of dimensions that correspond very closely to those of the cauldron under discussion. Curator Sarah Collins, of the British Museum Middle East Department, noted that if the cauldron is from this grave, it probably dates to the end of the Akkadian period (2300 – 2150 BC) or later.

A drawing from one of Woolley’s fieldwork notebooks of Grave PG/1422. The large cauldron found in this grave is depicted at the bottom left of the image.

A drawing from one of Woolley’s fieldwork notebooks of Grave PG 1422. The large cauldron found in this grave is depicted at the bottom left of the image.

Further information is provided by the illustration of this burial from Woolley’s field notes.  This shows a large cauldron on its side at the foot of the burial.  The fact that the cauldron has what appear to be woven fibres preserved on one side could support the idea that it is the one from site PG 1422.   Most Ur burials had a floor of matting. Usually the only surviving evidence of this is where it has been preserved on metal surfaces. Features of this type are known as Mineral Preserved Organic remains (MPOs).  This occurs when an organic substance, such as textile, leather, or natural or man-made fibre, is placed in contact with a metal surface over a prolonged period.  Metallic compounds from a corroding object inhibit the decay of organic materials and can eventually replace the entire structure. In archaeology, this process has ensured the preservation of the exact form of textile and other materials which otherwise would have been entirely lost.

The woven fibres are obscured by paraffin wax, although still recognisable.  Woolley observed that the pattern of the matting lining the burial was unusual and included a drawing of this in his field notes. Identifying how much of the mineral-preserved woven fibre survives, identifying whether it is matting, and whether it shows the pattern of the matting identified by Woolley are all questions to be explored.

A drawing from one of Woolley’s fieldwork notebooks of the matting that lined Grave PG/1422.

A drawing from one of Woolley’s fieldwork notebooks of the matting that lined grave PG 1422.

Also of potential interest is a crust of sooty deposit that is readily visible on the exterior of the cauldron wall and around the rim. Similar dark material is found embedded in the soil on the inner surface of the cauldron, where a section of soil has broken away from the metal surface. It is possible that this material could provide evidence of what the cauldron was used for. For example, traces of lipids (fats) could suggest that the vessel was used as a cooking pot but to prove this it would be essential to find a sample untouched by Woolley’s paraffin wax.

My aim is to stabilise the cauldron and secure it, as far as possible, for the future.  Close on the heels of this, through investigative conservation, I’d hope to extract information from the object, in the least intrusive manner, that will be of use in future research.

This process requires thought and care. For example, removing the obscuring layer of waxed calico and soil within the cauldron could lead to its complete collapse as it is in such a fragmented state. Further, as the object is also an example of Woolley’s excavation practice, there is an argument for this material to be preserved (providing that it is not now causing damage to the object).

First, the cauldron must be secured, supported and stabilised.  Next, it should be X-radiographed to identify how much of the metal of the cauldron body survives and possibly also to help glean information about structure and technology.  Further work, including analysis of the sooty deposits, and study of the mineral-preserved woven fibres, would all add to the body of data about the cauldron.  Methods of removing wax to reveal the surface of the object and the woven fibres could be explored with the support of Organics conservation colleagues.

How much can be achieved within the bounds of the current project, beyond the essentials, remains to be seen, as there are many more objects to assess and treat, but certainly these observations on this cauldron will be documented and thoughts on future investigations outlined.

So, from what initially appeared an unpromising corroded mass, a range of possible investigations has evolved which could help reveal more about the technology, use and significance of this vessel, not to mention helping establish its identity within a particular assemblage.  Although a humble object compared to the known treasures of Ur, it is potentially a small treasure house in itself of culturally significant information.

To conclude, Woolley’s tantalising notes on burial PG 1422:

‘This was the first grave which, on internal evidence, we could confidently assign to a period intermediate between the early cemetery and that of the Sargonid age:.. Even the Arab workmen recognised that it was in some way unlike any of the 1400 graves previously dug, and were greatly interested in it.  Their interpretation of some of its characteristics is perhaps worth putting on record: the unusual richness of his personal ornaments meant that he was young as well as wealthy; the number of weapons in the grave and the great size of the spear-heads meant that he was a fighting man and a warrior of note; but when they saw the cauldron at the foot of the coffin, a cauldron very much larger than the norm, they agreed that he was the leader of a band of robbers or else the sheikh of a clan; for only one holding such a position and having numerous followers to feed would require so huge a cooking-pot’ (C. L. Woolley, Ur Excavations: The Royal Cemetery, II, (1934), pp.186-187).