Monthly Archives: October 2017

A Columnar Matter Part I: The Technical Examination of a 3rd Century BCE Mosaic Column from Al Ubaid

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Marci Jefcoat Burton

My first project as a curriculum intern with the Penn Museum Conservation Department involves the conservation of a mosaic column from the Ninhursanga temple site of the ancient Mesopotamian city of Tell al-Ubaid in Iraq (column in digital collections: (B15887.1 – 15887.4). Dated as 2400 – 2250 century BCE, the column was excavated sometime between 1919 – 1924 as a pattern of alternating triangular and diamond shaped shell, pink limestone and shale tiles. Fortunately, the years of resting in the compacted dirt of the burial environment preserved the shell and stone tesserae and maintained their original conformation. The original column interior, more than likely palm logs, did not survive the centuries of burial.

Figure 1 (left): Before treatment image of the four column sections stacked together to make a mosaic column.
Figure 2 (right): Reconstructed façade of the Ninhursanga temple of Tell al Ubaid. The columns were originally believed to be outside the entrance of the temple doorway, although it is not certain if both columns were on the exterior or interior of the building. (Both images courtesy of The Metropolitan Museum of Art. (2003). Art of the First Cities: The Third Millennium B.C. from the Mediterranean to the Indus. The Metropolitan Museum of Art: New York)

Without a support, the delicate tesserae were lacking a method of storage and display. Working with the materials available on site and with technology available in the early 20th century, the archaeological team constructed four drums to mount the tesserae into four stackable sections. Although reports attribute the original 3rd century BCE binding medium as bitumen (i.e., asphaltum, tar, pitch) to hold the tesserae in place on the original wooden supports, the 20th century excavation team reconstructed the shell and stone mosaic pieces with a grey plaster. In addition, only half of each drum holds original tesserae, and the remainder of each section is filled with a painted plaster reconstruction.

Figure 3: c. 1920s, on-site with the recently assembled tesserae onto the wire mesh and wood drums. (Image courtesy of http://www.mesopotamia.co.uk/tombs/story/page07b2.html).

X-radiography of one of the drum sections revealed that each drum is constructed as a hollow metal mesh cylinder with wooden caps on each end, and several nails to keep the cylinder together. After 100 years in this conformation, the drums have become problematic for the long-term display of the tesserae. Fluxuations in temperature and humidity, as well as the weight of the tiles and the thick, rigid plaster have caused opposing shifts in the internal structure, leading to the formation of cracks in the plaster and several tiles to dislocate and fall from the support.


Figure 4: X-radiographs of column section B15887.3 detailing the inner drum structure consisting of an open wire mesh and hollow interior. (Left (a)): X-radiograph of the column section side reveals the radiopaque grid pattern indicative of a metal mesh. (Right (b)): X-radiograph of the column section top, revealing numerous nails in various locations that hold the cylindrical drum together. (X-radiographs courtesy of Julia Commander (2016)).

The column, with all four sections, is one of the many objects selected for exhibition in the upcoming Middle Eastern Gallery (scheduled to open in Spring 2018). Therefore, it was decided it was time for the over 4,000 year old tesserae to be removed from the hollow wire mesh supports and then remounted onto a structured, solid support made with materials that will prevent structural damage and be sustainable for its preservation and long-term display in the gallery. Following a treatment protocol implemented successfully on one of the four column sections by Julia Commander (WUDPAC, Class of 2017), I will deconstruct the tesserae from the current supports, clean and repair each piece, and remount the tesserae in their same arrangement to new cylindrical supports made from solid, very dense Ethafoam measured to the exact shape for each section awaiting treatment. Stop by the Artifact Lab to see the progress of the column treatment, which is already underway, or stay tuned for a follow up blog post!

Figure 5: Start of the disassembly of the shell, pink limestone and shale mosaic tesserae from column section 2. Note the color difference of the large painted plaster fill on the left versus the original tesserae on the right. Several breaks are also observed in the inlays (most notably the beige shell pieces) and a layer of dark, brown grime has accumulated on the surface overall.

Cleaning – it’s complicated

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by Lynn Grant

Not that long ago, a museum colleague was heard to say “I suppose cleaning counts as conservation” in a doubtful voice. We conservators found this both appalling and amusing as cleaning is a huge part of what we do. And knowing when and how to clean is a big part of our education. Using the wrong methods can permanently damage an artifact. Those of us who finished our conservation training more than ten years ago mostly relied on the rule of thumb ‘try gentlest methods first’. But there have been rumblings in the field about better ways to do things, with terms like Modular Cleaning Systems and Gel Cleaning drifting by. Clearly this was something we needed to know more about.

Richard Wolbers (in blue polo shirt) demonstrates basics of cleaning gel production to Museum conservators and interns

Fortunately for us, one of the ‘rock stars’ of gel cleaning research, teaches nearby at the Winterthur/University of Delaware Program in Art Conservation. Richard Wolbers, who describes himself as a ‘Cultural Materials Engineer’ to reflect his interest in applying new ways of thinking about conservation issues, is Associate Professor at WUDPAC and has graciously lent us his expertise on specific projects previously (one example here). But now that we have so many conservators and interns working on different projects and with a major campaign to reinstall our Egyptian Galleries after 90 years about to start, we asked Richard to give us a two-day workshop on the basics of gel cleaning. This was an abbreviated version of week-long workshops he gives around the world but we certainly squeezed a lot of learning into two jam-packed days.

The conservators and interns get into gel (and emulsion) production!

Richard has basically turned much traditional conservation ‘wisdom’ on its head: looking deeply into the complex interactions among surfaces, dirt, and cleaning materials and using his observations to develop new approaches to cleaning. Even gels aren’t the new frontier anymore; custom made emulsions may allow conservators to use water and solvents in combination when the surface is easily damaged by them when used in liquid applications. Many of the techniques and materials that Richard uses come from the cosmetics and food industries. In fact, as we listened to his explanations, I kept thinking of the Molecular Gastronomy movement. Some of our new cleaning tools have as much relation to our old way of doing things as this does to your grandma’s chicken soup:

Chicken soup spheres (http://jordancaterers.blogspot.com/2013/07/chicken-soup-spheres.html)

It’s a brave new world for conservation cleaning….

Conservation (training) in action

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Our new curriculum intern, Marci Jefcoat Burton, was here for only couple weeks before we seemingly threw her to the wolves. That is, we asked her to work in the Artifact Lab and handle the open window sessions.

Marci describes her work to 2 visitors during an open window session

But we knew that Marci would do a stellar job working in front of the public and answering their questions. Although Marci is technically an intern, she already has extensive experience in conservation. In fact, as a curriculum intern, this is her final year of her graduate studies in conservation (she will complete her MA at the UCLA/Getty Master’s Program in the Conservation of Archaeological and Ethnographic Materials in June 2018).

One does not get to this point in their conservation training without a lot of experience working in conservation labs – to even be considered for an interview at many of the graduate programs, prospective students must have completed hundreds of hours interning with a conservator. More information about the path to becoming a conservator can be found here on the AIC website.

Marci is working on a number of projects here at the Museum, at least one of which she is basing in the Artifact Lab.

Marci working on a mosaic column drum from Al’Ubaid, Iraq (left) and examining an Islamic bowl at the microscope (right).

Stay tuned to the blog for more information about the column drum (in image above), and visit the Artifact Lab during open window hours for a chance to speak with Marci about her work!