A Columnar Matter Part III: The Conservation and Installation of a 3rd Millennium BCE Mosaic Column from Al ‘Ubaid

By Marci Jefcoat Burton

As a last installment of the mosaic column from Tell al-Ubaid in Iraq, we are pleased to announce the treatment and remounting of the 4,200(+) year-old shell, pink limestone, and black shale tesserae is complete (Figure 1)! After a number of years in collection storage, the recently conserved column is now in the Middle East Gallery, and ready for visitors when the exhibit opens this Saturday, April 21, 2018. The treatment process was a dynamic collaborative project, involving a team of seven conservators to clean, repair and re-mount hundreds of triangular and diamond shaped tesserae over the span of 18 months.

Figure 1: The previous column support (left), with all tesserae deconstructed from each section. Only mounting materials, such as plaster ground and reconstructions, remain on the supports. (Right) The newly mounted tesserae on Ethafoam column supports.

The tesserae were originally mounted at the archaeological site in 1919 – 1924 on four hollow cylindrical sections made of wire mesh and burlap. The tesserae were imbedded in a thick layer of plaster, and the resulting weight on a somewhat flexible base eventually became a structural problem. In addition, each column section had a large area of plaster reconstruction to continue the mosaic design around the column. For a memory refresher of the previous condition and treatment protocol, visit our blog posts, column blog 1 and column blog 2.

After months of cleaning every tessera and adhering many fragments back together, the tesserae were mounted onto a new support made from solid Ethafoam, a chemically stable and dense foam (Figure 2). Each new column section support was reconstructed to the same measurements as the wire mesh and burlap supports. The previous use of plaster proved too rigid and heavy in the original mounting system, causing many cracks to develop in the plaster and tesserae to loosen over time. For these reasons, plaster was not used again, and the tesserae were mounted to the Ethafoam supports with an acrylic paste (Paraloid® B-72 (ethyl methacrylate (70%) and methyl acrylate (30%) copolymer) in acetone bulked with glass microspheres) toned black with dry pigments. This is lighter in weight compared to plaster, and compatible with the shell and stone materials. The black acrylic paste was made to resemble bitumen, a pine resin material used by the Mesopotamians to originally mount the tesserae to the c. 3rd Millennium BCE column.

Figure 2: Mounting process of column section #2. The cleaned and repaired tesserae are mounted to the Ethafoam cylindrical supports with Paraloid® B-72 (ethyl methacrylate (70%) and methyl acrylate (30%) copolymer) in acetone bulked with glass microspheres and toned black with dry pigments to mimic bitumen. Spatulas were used to spread the acrylic resin on the support and tesserae were imbedded into the mixture.

All four column sections stack and connect with an internal wooden dowel system. To accommodate the large areas that were once plaster restorations, our Photo Studio printed high resolution, archival images of the tesserae, which were custom scaled and fit to each column section (Figure 3). The digital photo fills integrate a complete mosaic design to give the appearance of a fully mosaicked column (Figure 4). This is a great example of how recent technological advancements help conservators with approaches to treatment and display options.

Figure 3: (From left), Conservation Interns Tessa Young, Alyssa Rina and Jennifer Mikes installing digital photo fills to the top and bottom mosaic column sections.

Figure 4: (a): Column section #2, after remounting tesserae. The locations with previous plaster reconstructions are padded with Volara (closed-cell polyethylene foam). (b): Column section #2 after pinning archival photo fill into place over the Volara.

The mosaic column, and over 1,500 objects await your visit in the Middle East Galleries (Figure 5)! To our visitors in the Artifact Lab who witnessed our many, many hours of treating these column sections, we thank you for your brilliant questions, comments and curiosity about the tesserae and our conservation process during our Open Window Sessions. You will find the assembled column has transformed into an impressive and complete piece, and we hope you enjoy it as much as we do!

Figure 5: Bob Thurlow (Special Projects Manager) and Marci Jefcoat Burton (Conservation Curriculum Intern) installing the four mosaic column sections in the Middle Eastern Gallery.

Ancient faces in the Middle East Galleries

Our new Middle East Galleries open next week and they will feature over 1200 artifacts from our collection, including many iconic objects like the Ram in the Thicket, the Bull-headed lyre, and Queen Puabi’s headdress. Oh, and for those of you who are always asking about our cuneiform tablets, do we have a treat in store for you – there are dozens and dozens in the galleries. The majority of the objects in the exhibition were excavated by Penn archaeologists, many nearly a century ago.

ALL of these objects came through our Conservation Labs to prepare them for the galleries and many needed significant treatment in order to ensure their stability for long-term display. Our Middle East Galleries (MEG) team has worked diligently and tirelessly on this project – you can read more about some aspects of this work on the Penn Museum blog here.

The triumphant column team poses next to the 4 recently conserved mosaic column drums from Tell al-‘Ubaid, Iraq. This project took months to complete.

In just over a week, visitors to the Museum will have the opportunity to get up close and personal with these newly-conserved objects. Everyone will be drawn to the highlight pieces mentioned above and here, but the other pieces are worth lingering over too. It’s usually impossible to see them as closely as we do during the conservation treatment process, so I thought I’d give you the opportunity to see 2 small but beautiful objects closer than you can in the galleries.

B8997 (left) and B9026 (right)

These 2 female figures, both excavated from Nippur, Iraq, will be on display in the same case in the Middle East Galleries. They’re small, just several inches long. The figure on the left was likely a doll which would have had articulated arms; you can see the holes where they were once attached. Fortunately, both artifacts required very little treatment. B8997, the figure on the left, does have a large, but stable crack that did not require any treatment. Examination under the binocular microscope revealed small amounts of burial dirt on both figures which had escaped previous cleaning campaigns, so both were carefully surface cleaned to remove this soil.

Detail of B9026 before (left) and after (right) cleaning, 7.5X magnification

As I worked on these figures, I captured some images with the camera attachment on our Leica microscope. Both objects are made of bone and are delicately carved. The reverse side of the doll’s head has an unworked area that nicely shows the cancellous (or spongy) bone features.

B8997 detail of front (left) and reverse (right), 7.5X magnification

Their time in the lab was brief – they only stayed for a day or 2. But in the midst of the hustle and bustle of preparing for these galleries, it’s nice to take a moment to appreciate the details.

The Middle East Galleries open to the public on Saturday, April 21. Our department has a few loose ends to wrap up with that project (and a few loose ends on the blog – stay tuned for a last blogpost on the mosaic column treatment) but we’re already turning to our next big tasks – the renovation of our Mexico & Central America Galleries, Africa Galleries, and Egyptian Galleries.