A glimpse of upcoming changes

There are a few new objects on display in the Artifact Lab this week, which give visitors a glimpse of upcoming changes in the museum.

Newly-installed case with objects slated for the renewed Mexico & Central American Gallery

These 4 pieces were recently conserved in the Artifact Lab to prepare them for installation in our forthcoming Mexico & Central America Gallery (from left to right: a stone metate from Costa Rica 11819, two burnished ceramic jars from Mexico 31-41-34 & 87-42-1132, and a ceramic tripod vessel from Costa Rica 2013-11-1) .

You can see many other objects that will be going into that gallery, both on display in our current Mexico and Central America Gallery as well as being worked on in the Artifact Lab.

Artifacts currently being treated in the Artifact lab.

Visit our Building Transformation website to learn more about this gallery, which will look something like this:

#Transformation Tuesday: Getting our Ducks in a Row

The transforming treatment of the Al’Ubaid frieze of three birds (B15883) from the new Middle East Galleries in now complete! (To be more correct, they are probably doves not ducks.) More information about the frieze can be found here. Click here for more information on the exciting new galleries, opening this April!

The frieze before treatment

The frieze after treatment

Originally, the three stone birds (initially called ducks but now identified as doves) would have been surrounded by black shale tesserae and the borders would have been copper alloy sheets. The frieze would have originally looked much like the marching bulls frieze. Unfortunately, neither the shale pieces nor the copper alloy borders made it. The birds had been embedded in a plaster background carved to look like the shale tesserae, and the borders were made from modern machined copper alloy sheets.

The old support system had to be removed due to some condition issues and to prepare the frieze for long-term exhibition. Once taken off, the grimy birds could then be laser-cleaned. The blog post about laser-cleaning them can be found here.

Applying the bulked Paraloid B-72 to the Ethafoam© support

Although the only ‘real’ parts were the stone birds, the curator wanted the entire frieze to be reconstructed to help visitors put the birds in context. It will be displayed next to the marching bull frieze.

After cleaning, the birds were adhered onto a piece of dense archival foam. The black tesserae background was created with Paraloid B-72 (ethyl methacrylate and methyl acrylate copolymer) bulked with glass microballoons and toned with dry pigments. Bulked Paraloid B-72 is stable, reversible, and easily manipulated with either solvent or heat. The shallow lines to make it appear there are tesserae were put in with a heated spatula. The copper alloy borders were also created with Ethafoam© coated in bulked Paraloid B-72 tinted in various shades of green to mimic copper corrosion. The fills in the ducks were inpainted with acrylics to integrate them better.

After all that, the ducks look much happier!

The frieze after treatment and ready for display

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#Transformation Tuesday: New Year’s Edition

By: Céline Wachsmuth

It’s Tuesday and that means it’s time for another transformation story. This one comes from an object going into the Middle East Galleries (click here for more information on the exciting new galleries, opening this April!).

It’s hard to believe the first month of January is almost over! Many people make resolutions for the New Year, hoping to make an improvement, big or small (myself included, I have a Google doc with a list of resolutions). Most resolutions are easier said than done, including the prevalent resolution to shave a few pounds. This bowl had similar thoughts, but made losing some weight look like a piece of cake!

Bowl before treatment (left) and after treatment (right)

This bowl had been repaired in the past, but the joins needed to be taken down because the old adhesive was failing. The bowl was pretty clean when it came into the lab so it wasn’t long before I began solvent testing the adhesive in order to make a vapor chamber. The adhesive was soluble in acetone and most of the sherds separated with gentle prodding after eight days in a vapor chamber. The old fills (made of plaster), however, did not budge. This was probably due to the likelihood that they had been cast in place.

Outlines of Old Fills
Fill outlined in dark blue was dremeled out
Fills outlined in light blue were softened with deionized water and then removed

These ounces had to go! When a fill resists detachment by solvent, other, usually mechanical, methods have to be implemented. One mechanical treatment is to use a dremel, just like the one you might use at home for some smaller detailed work, to carve away the fill. This is tricky because the dremel can put the object at risk if used improperly. Once I was all set up and had been shown the proper technique, I slowly moved around the entire area of the fill.

using the dremel to remove the fill

two of the sherds sitting in a bed of glass beads while the adhesive sets

Once the large fill was removed and those ounces had been shed, it was time for some TLC. I cleaned the break edges on each sherd with acetone (for the sherds previously joined with adhesive) or deionized water (for the sherds adjacent to the old fills). All the break edges were then coated with a dilute solution of Paraloid B-72 (ethyl methacrylate methyl acrylate copolymer) and the sherds were put back together with a 50% solution of Paraloid B-72 in 1:1 acetone:ethanol. Two small areas of the bowl had some gaps that needed to be filled; one for added structural stability and one to help complete the shape. This was done using a mixture of 3M microballoons, Paraloid B-72 in 1:1 acetone:ethanol, acetone, and some dry pigment to approximately color match the fill to the bowl. The fills needed some additional color to help blend in more and they were painted with light washes of acrylics.

This bowl made losing a couple ounces look easy even though we all know how much work really has to go in to something transformative! Thankfully, it’s only the beginning of the year and there is plenty of time to make your own transformations. Just like there’s plenty of time for another transformation to happen in the labs before our next Transformation Tuesday post – stay tuned!

PS – If you’re looking for some “ancient workout tips” check out these fun suggestions

A Columnar Matter Part II: The Conservation Treatment of a 3rd Millennium BCE Mosaic Column from Al ‘Ubaid

By Marci Jefcoat Burton

As a follow up to my previous blog post, conservation treatment of the second of four sections comprising a mosaic column from Tell al-Ubaid, Iraq is well on its way! For a quick recap, the column is dated to 2400 – 2250 BCE (Figure 1). After centuries of burial, the triangular and diamond shaped shell, pink limestone, and shale tesserae (also referred to as tiles), were excavated in 1919 – 1924. The original wooden column interior did not survive the centuries of burial, so after excavation, the tesserae were mounted with plaster to four hollow cylindrical supports of metal mesh covered with burlap. After nearly 100 years, shifts in the internal support have caused structural instability to each section.

Figure 1: (left) Before treatment image of the four column sections stacked together to make a complete column. Image 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) (right) Column section 2 detail, before treatment.

First step of treatment: Remove tesserae from the current support.

The plaster was softened with distilled water applied by brush, then carved away to expose the sides of the each tessera. The tesserae could then be separated from the plaster and burlap backing one by one (Figure 2). Like the first slice of pie, the first piece was the most difficult to remove. Once extracted, access to adjacent tesserae became easier.

Figure 2: (left) Removing plaster surrounding the tesserae with a scalpel blade. Plaster was first softened with distilled water. (middle) Carefully extracting a shell tessera from the plaster. (right) Shell tessera after removal from column section.

The tesserae were removed from the support and placed on an enlarged reference photo in a tray to maintain the order of composition (Figure 3).

Figure 3: All tesserae were removed from the support and placed on top of a rolled out image of the column section to maintain their original placement. All that remains on the exterior of the cylindrical support is a layer of grey plaster and previously filled areas. As a bonus, the Egyptian female child mummy named Tanwa can be seen in the background, just outside of the Artifact Lab window!

Second step of treatment: Cleaning

After removal from column section 2, all tesserae were covered with a layer of powdery plaster, which was removed with distilled water applied with hand-rolled cotton swabs. Medical scalpels were used to gently lift and remove thick remnants of plaster as well as adhesive from previous repairs. In addition, years of dark-brown dirt, dust and grime were removed with distilled water, and Stoddard solvent (a petroleum-derived organic solvent) was applied to the pink limestone and shell pieces to remove greasy grime trapped in the surface (Figure 4).

Figure 4: (left) Removal of adhesive and plaster remnants from a diamond shaped tesserae using a medical scalpel. (right) Shell tesserae being cleaned with distilled water. Note the dark grey-brown grime picked up on the cotton swab.

Third step of treatment: Repair

Once cleaned, tesserae that exhibited breakage such as cracks, detachment, and delamination were repaired with a thin layer of a semi-viscous solution of Paraloid® B-72 (ethyl methacrylate (70%) and methyl acrylate (30%) copolymer) resin in acetone. The majority of the shell tesserae experienced separation between the layers comprising the shell. Some even separated into several pieces, making their reassembly somewhat of a puzzle (Figure 5)!

Figure 5: (left) A triangular shell tessera delaminated (separated) into six pieces. (right) The same shell tessera with all pieces adhered together with Paraloid® B-72.

The shale was even more temperamental to remove from the column section (Figure 6). Shale is a soft sedimentary rock composed of mud, clay, and minerals, such as calcite and quartz. The inherent nature of the shale causes breakage and crumbling. Water can remove particles from the shale surface, therefore these pieces were cleaned with dry brushes and if needed, cotton swabs lightly dampened with distilled water.

The most resilient material was the pink limestone. While some pink limestone tesserae are weathered on the surface, most likely from centuries of burial, these tiles exhibited very little breakage and cleaned up nicely with distilled water and Stoddard solvent (Fig. 6).

Figure 6: (left) A diamond shaped shale tessera exhibiting a lack of cohesion, best observed around the edges, which caused cracks and areas of material loss. (right) A resilient triangular pink limestone tessera with a weathered surface, noted by the lighter, speckled locations. The pink limestone tesserae have strong cohesion and required very little repair.

After a month of cleaning and repair of the shell, pink limestone and shale tesserae, their overall appearance is quite transformative. The tesserae look brighter and truer to their original colors (Figure 7). This is especially the case for the pink limestone, which went from a dark peach-brown, to a brighter light-pink hue.

Figure 7: (left) Shell, pink limestone and shale tesserae after removal from the former support, and kept in their original arrangement. (right) All tesserae after cleaning and repair, ready for re-mounting to a new support.

…..What’s next?

The next phase of treatment for section 2 of the mosaic column is to mount the shell, pink limestone, and shale tesserae to a new solid cylindrical support. More information and updates on the column treatment progress will be featured in an upcoming post, so please stay tuned!

#Transformation Tuesday ft. The Big Guy

By: Céline Wachsmuth

It’s #TransformationTuesday! And that means I get to show off a wonderful transformation that happened right in the Lower Egyptian gallery here at the Museum.

Before Treatment Shot of the Big Guy

After Treatment Shot of the Big Guy

Tah-dah! Looks great, doesn’t it? The Big Guy looks so much better. (I affectionately nick-named this block “Big Guy” because it’s the heaviest block on this side of the wall (it weighs approximately 720 pounds). If you’re in need of some context for this project, check out this Kaipure Catch Up)

Though there isn’t much visible difference between these two photos, in terms of the stability of the block’s surface, much has changed. All in all, this treatment took me about two months to complete and it was quite the journey.

I began my treatment by condition mapping the block in Photoshop and then surface cleaning with gentle vacuuming. Once the dirt immediately on the surface had been removed, I used a variety of sponges and erasers to clean the more stubborn grime. In just these first two steps I realized how fragile much of the surface was. Small flakes would break off easily and not always predictably. Swabbing with a cotton swab was no different and in some cases was more problematic. I proceeded slowly and carefully. Once the Big Guy had been safely cleaned, you could really see his brightly painted surface. The colors were more visible, but so were the fragile and lifting areas. I next faced the biggest challenge of this treatment: how to efficiently and effectively stabilize and consolidate the surface.

Photoshop Condition Mapping of the Big Guy

I began stabilizing all the lifted areas by injecting a dilute adhesive under the surface using an insulin syringe. This worked for some areas but caused some of the surrounding surface to darken. If it came in contact with the surface, the needle also had the potential to disturb it and cause a piece to break off. I then tried to apply the adhesive by brush; I saturated the brush with adhesive and gently tapped the exposed stone next to the prepared surface, wicking the adhesive underneath. This worked but had many of the same issues as the syringe. Both application methods would have taken a substantial amount of time, as almost all of the surface was in need of some consolidation. I began to explore other options for effectively consolidating the surface. In speaking with conservators in the department, we decided to try applying the adhesive via spray canister.

Preval Spray System

Before spraying the entire block, we tested it to see how even the spray application would be and if it would cause any darkening or staining. I was very happy with the tests but thoroughly discussed all the potential shortcomings of this application method with Kaipure project supervisor Molly Gleeson. Spraying the adhesive wouldn’t penetrate below the prepared layer and would only provide superficial consolidation. For those areas that were significantly lifted, I went around with a higher percentage of adhesive and used the brush method of application mentioned above. Once I was satisfied those areas had been stabilized, I sprayed a layer of adhesive on the surface, let it dry completely, and then applied a second layer in areas that were still more concerning. The Big Guy was much more stable and happier but you can’t see any evidence of this because the adhesive is clear!

(I bet if you ask him though, he’d tell you he felt much prettier!)

This figure grabbed a bunch of food to celebrate the Big Guy’s transformation! In actuality, this figure is bringing food for the REAL Big Guy, Kaipure

The Big Guy was almost complete but I had one more task to finish before he would be ready to be handled. Many areas of loss had unprotected edges at risk of being lifted off the surface. Take this area for example, there are quite a few spots with unprotected edges ready to break off with added pressure. 

Detail of unprotected edges

To solve this problem, I edged (put up a protective and supportive layer of material around the exposed edge) those spots with Modostuc. Notice the white spots now on his body?

Can you see the white areas?
Detail of area of edging on figure

I went around to the many places on the Big Guy with unprotected edges and did the same thing. Once I was satisfied all edges had been protected, I painted over all of them with watercolors, a process called “inpainting”. And, if I did my job well, you can’t see it!

Can you find the areas of edging?
Detail of inpainting

The Big Guy is now stable and ready to be moved off-site until the next phase of treatment: re-installing him in the Museum with his many brothers and sisters! This is all part of a larger picture of transformation (for more information on the museum Building Transformation Campaign, click here). It’s a transformation inside a transformation! Inception, anyone?

Two weeks ago, conservator Alexis North posted about one of her recent treatments where the before and after treatment photos are indeed worlds apart and more what you might expect from a Transformation Tuesday post (see her post here). However, don’t judge a book by its cover or an object by its treatment photos! Though you can’t always see the changes, rest assured that once an object passes through conservation it has been changed for the better. Stay tuned for more of our exciting (and perhaps surprising!) Transformation Tuesday series posts!

The Kaipure Conservation Project is funded through a generous grant from the American Research Center in Egypt (ARCE) Antiquities Endowment Fund (AEF) which was established though a grant from the United States Agency for International Development (USAID).

Coming clean

by Alexis North, Williams Project Conservator

The renovation of our Mexico and Central America gallery will involve the conservation and installation of over 200 objects. Some are currently on display in the gallery, but many have never been exhibited before. One of these “new” objects (actually acquired from the World’s Columbian Exposition in Chicago in 1893) is this carved stone figure from Ecuador. It depicts a human man, possibly a king, seated on a throne.

Before treatment views of 12676, a stone figure from Ecuador.

It has an overall dark, somewhat shiny surface. At first glance, it looks like it may have been carved from a smooth black stone like hematite. However, once I was able to look at the figure more closely in the lab, I could tell there was something suspicious about its surface and overall appearance. The surface had a waxy feel, and upon closer inspection, I could see spots of wax on the surface. These waxy areas were very visible under ultraviolet light:

UV fluorescence image of the proper right side of the figure. The bright yellow-white spots are wax.

When I looked at the bottom of the figure, my suspicions were confirmed. Here you can see the bottoms of the feet of the figure and chair, which appear lighter and grey, and much more like stone than the odd waxy sheen of the rest of the surface.

Before treatment image of the bottom of the figure, showing the true surface and appearance of the stone.

I talked to the American section curator, keeper, and other conservators here in the lab, and we all agreed that this type of figure would not have had any sort of surface coating applied during its original use. It is likely that at some point after excavation, the piece was coated to give it more of an even, dark, shiny surface, which was seen as desirable by art dealers and collectors at the time, followed by a wax as a “protective” layer.

In order to prepare this object for display in our new gallery, the old surface coating had to go. It was misrepresentative of the object’s appearance, and the wax was collecting dust and grime. After our incredibly successful gel cleaning workshop with Professor Richard Wolbers, I decided that an emulsion gel would be ideal for removing this old coating.

I started by testing a number of aqueous cleaning solutions in a rigid agar gel. Small punches of gel with each solution were placed on the surface of the figure, and allowed to sit for 20 minutes. The small pores in the agar gel help it act as a sponge, holding the solutions against the surface and pulling the surface coating into the gel using capillary action.

During (left) and after (right) testing different cleaning solutions with a rigid agar gel.

The agar gel samples, after removing them from the figure’s surface.

And the results of my tests were pretty clear! All the solutions tested were successful in removing some of the surface coating (which is unusual!) but Solution A (deionized water with 0.5% citric acid, buffered to a pH of 6.0) clearly pulled the most grime and surface coating away. I performed a second test using Solution A in a xanthan gum gel, which is viscous but not rigid, resists penetration into the surface it is applied to, and has an emulsifying behavior when agitated which helps to pull out and hold on to the material being removed.

I also tested several solvents on the surface, and found that iso-octane would remove the wax, and acetone and benzyl alcohol both cleared some of the grime. I decided to make a xanthan gel mixture utilizing both cleaning Solution A and a combination of iso-octane and benzyl alcohol. This mixture, when tested on the surface, very successfully removed the surface coating better than Solution A on its own, revealing a lighter, gray-green micaceous stone underneath.

The results from testing xanthan gel mixtures by swabbing them on the surface.

Once the cleaning method was identified, it was simply a matter of systematically removing the coating. I worked in sections, by first applying a layer of octamethylcyclotetrasiloxane (D4), a silicone-based solvent which does not mix with water or the solvents used in the gel. The D4 fills the pores of the stone, and acts as a barrier that keeps the gel, solvents, or surface coating from penetrating into the stone during cleaning. Then I brushed on the xanthan gel mixture, and gently agitated it with a paintbrush over the surface to pull up the surface coating. Once the gel had turned a dirty brown, indicating that it pulled up the coating (see below), I removed the gel with cotton swabs and then cleared the area with deionized water. It was an extremely satisfying, if a bit goopy, process.

Left: After the left side of the seat was cleaned using the xanthan gel. Right: The cleared gel, you can see how dirty it got!

And here are some before and after photos of the figure. The difference is so clear! I believe the coating may have been applied to obscure the scratches you can see on the front of the figure, but overall it looks so much better now that the original material is visible.

After treatment images of the figure.

Front view after (left) and before (right) cleaning.

You can see this figure when we open our new Mexico and Central America gallery in late 2018!

Transformation Tuesday

Inspired by our Building Transformation campaign, we are starting a series on this blog called Transformation Tuesday. At least one Tuesday a month, we will write a post featuring conservation projects underway that are contributing to the Penn Museum’s Building Transformation, along with interesting tidbits that we are learning about the collection and the Museum building as we work.

For instance, we are in the process of fully documenting the architectural elements of the palace of Merenptah currently on display in the Lower Egyptian Gallery, in preparation for the future reinstallation of this material on the 3rd floor of the museum. This includes documentation and research on a variety of levels, and just last week, the palace elements were laser scanned** in order to document them as accurately as possible before they are moved.

Black and white targets placed around the Lower Egyptian Gallery as part of the laser scanning process (left) and the scanning of a column in progress (right)

To supplement the laser scanning, we are creating condition maps of each of the architectural elements. These are big pieces, so it requires us getting up on a lift so that we can examine all surfaces of the columns, gateways, and doorways.

Last week, we began by examining and documenting one of the palace doorways. We always thought that this doorway had been up since 1926 like the rest of the palace, but in the photographs from the opening of the Lower Egyptian Gallery in 1926, this doorway isn’t there!

Lower Egyptian Gallery in 1926 (left) and in 2017 (right). Note that the doorway on the far right in the 2017 image (indicated by the red arrow) is not in the 1926 photo.

We know that the Lower Egyptian Gallery opened on May 19, 1926. So when was that doorway installed? Well, when we got up on the lift to examine it from above, we could see that there were some very minor differences in the way that it was installed, but we also saw a scrap of newspaper stuck between the plaster restoration on one side and the wall.

A piece of newspaper wedged between the wall board and plaster restoration and the wall behind the doorway.

And this piece of newspaper has a date on it! It is a scrap from the Philadelphia Bulletin dated to Thursday July 22, 1926. So it seems that they intended on installing the doorway for the opening, but may have run out of time, and installed it just a couple months later. This isn’t a huge revelation, but it is an example of some of the fun investigating that we do as part of our work to reconstruct the history of our galleries and the objects that are installed in them.

Stay tuned for more Transformation Tuesday blogposts!

**The laser scanning of the palace of Merenptah was funded through a generous grant from the American Research Center in Egypt (ARCE) Antiquities Endowment Fund (AEF) which was established though a grant from the United States Agency for International Development (USAID).

Kaipure Catch Up

by Anna O’Neill

Hello again from the “Other Artifact Lab”! It’s been a while since we’ve checked in here from Kaipure’s tomb chapel and a lot has changed in Lower Egypt since the summer. Since June, we have been working to clean and stabilize the painted limestone walls of the Old Kingdom (2415-2298 BCE) mud-brick mastaba tomb chapel for a high-ranking Egyptian official named Kaipure. In the winter of 2015-2016, conservators Emily Brown and Madeleine Neiman worked to disassemble the tomb chapel wall from its wooden 1920s support and performed triage treatments (read more about that here) to keep the blocks safe from vibrations caused by construction next door. This past spring marked the start of the current phase of the project: cleaning and stabilizing the blocks so they can be moved to off-site storage in 2018.

If you’ve been through the Lower Egypt (Sphinx) gallery recently, you may notice some new and familiar faces in the lab. While Céline Wachsmuth and I (Anna O’Neill) have been working on the wall since June, in September we were joined by a third project assistant, Jonathan Stevens. 

The view from our lab space, with two of the blocks reflected in the foreground. We may be biased, but we think we’ve got the coolest lab-mate around.

Between all of us it’s been a very busy fall! We’ve continued to clean and stabilize each individual block from the wall, becoming familiar with some different techniques for cleaning, consolidation, infilling, and documentation, as well as repair methods used by the ancient Egyptians (more on these later). Dr. David Silverman, Curator-in-Charge of the Egyptian Section, stopped by to tell us a little more about the history and imagery of the chapel. We’re also improving our proficiency in fork lift handling as we move the pallets supporting the very heavy stones. Just a few weeks ago, we reached a very important milestone – we officially passed the halfway point, with more than half of the 59 blocks stabilized for their move off-site next year.

A view inside the lab. The largest blocks (up to 700 pounds!) are housed on the red shelves along the back wall; the ones covered in tissue are cleaned, consolidated, and ready to move off-site.

If you find yourself in Lower Egypt any time soon, you are welcome to come watch us work in the lab and read more about the history of Kaipure’s tomb chapel (on our new, informative signage!). While we don’t have open window sessions downstairs, we do occasionally find ourselves in the main Artifact Lab and we’ll be happy to talk about our work then. We’ve got more Kaipure blog posts planned, so keep your eyes open for updates and insights.

The Kaipure Conservation Project is funded through a generous grant from the American Research Center in Egypt (ARCE) Antiquities Endowment Fund (AEF) which was established though a grant from the United States Agency for International Development (USAID).

BIG changes, little details

On November 1, our Museum announced the commencement of our  Building Transformation  campaign, a monumental project which will include a full renovation of our building structure and reinstallation of many of our signature galleries, including our iconic Egyptian Galleries.

The first glimpse of this work will be the opening of our Middle East Galleries in April 2018. This is not news for readers of this blog – you have been hearing about the conservation work for this project for awhile now (for reference, see these related blogposts).

Graduate intern Marci Jefcoat Burton (standing) and pre-program interns Fallon Murphy, Jennifer Mikes, and Alyssa Rina during an open window session in the Artifact Lab (with one of the al-Ubaid mosaic columns in the foreground)

In fact, you can get a glimpse of several exciting projects that are underway for our Building Transformation right now, on a daily basis, in either of our 2 public conservation labs.

In the Artifact Lab, you will mostly see objects being conserved for the Middle East Galleries and for our Mexico and Central America Gallery, opening in November 2018.

An assortment of artifacts for the Mexico and Central America Gallery in various stages of conservation treatment.

Our other public lab is down in our Lower Egyptian Gallery. Work in that space is dedicated exclusively to conservation treatment of the carved and painted limestone blocks from the Old Kingdom tomb chapel of Kaipure.

A view of the Kaipure tomb chapel lab space in Lower Egypt

Project Assistant Anna O’Neill at work on a block in the Kaipure lab

While you can watch the conservation team at work most days in the Kaipure lab, unlike the Artifact Lab, it does not include open window sessions. But have no fear – the Kaipure team has promised to write some blogposts about aspects of their work, so stay tuned for more information on this project!

Big projects like the Building Transformation campaign come down to a lot of little details, and no one knows details like the Conservation Department. We hope you visit us to learn more about these details, and all the work underway to make these big changes possible.

Sometimes you just can’t get close enough (intern Celine Wachsmuth in the Kaipure lab)

To learn more about the vision of our Building Transformation, check out this ~3 minute video which captures the grandeur of the project (and features Project Conservator Tessa de Alarcon!).

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

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.