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Resurrecting a “Pretty Lady”

One of the most complex treatments undertaken in the gallery as part of “The Conservator’s Art” was the reconstruction of a crushed and broken cartonnage mummy mask, PAHMA 6-20106.

PAHMA 6-20106 before treatment.

The mask was purchased by museum founder Phoebe A. Hearst around the turn of the twentieth century. It depicts a young woman wearing a blue wig bound by a headdress decorated with a vulture and small rosettes. Stylistically, we can date the mask to the Ptolemaic Period (305 BC-30 BC). Due to the delicate painted design, the mask earned the nickname “Pretty Lady.” While the mask was being treated in the gallery, visitors often inquired as to whether such a  mummy mask would have been a luxury item affordable only to very elite members of ancient Egyptian society. The mask appears to be a high quality cartonnage piece, probably one that could have adorned the mummy of an upper middle class woman.  As Near Eastern Studies PhD candidate Elizabeth Minor explained, the mask was something a person would buy at (the ancient Egyptian equivalent of) Neiman Marcus, rather than Kmart.

PAHMA 6-20106 before treatment.

Condition-wise, the mask was not at all pretty. It was crushed, broken, torn, dented, flaking, and missing sections. The interior linen surfaces had been partially lined with coarse burlap in a failed undocumented repair effort. The first order of business was to retrieve cartonnage fragments and burlap lining from the interior of the head cavity.

PAHMA 6-20106 before treatment.

This revealed that the linen core on the back of the head was badly torn, creased and delaminating.

PAHMA 6-20106, detail of torn linen before treatment.

The back of the head was stabilized prior to beginning work on the fragmentary face. Creased linen and flattened cartonnage were relaxed with local humidification. Select areas were humidified by placing them in contact with pieces of Gore-tex, a water vapor permeable fabric, and placing a moisture source on the other side of the Gore-tex. Once the torn linen was rendered flexible and the tear edges realigned, the tears were mended and backed with Japanese tissue paper adhered with BEVA 371 film (a flexible heat-set synthetic adhesive that provided strong yet reversible joins).

Once the back of the head had been stabilized, the mask was lifted from the support and placed on a form in order to assess the back surface and work towards reconstructing the face. Yet more fragments of cartonnage and flakes of detached painted surface were found beneath the back of the wig. Most of the flakes of blue wig surface were reattached with methyl cellulose, a water-soluble cellulose ether.

PAHMA 6-20106 during treatment in the gallery, after stabilization of the back of the wig and before reattachment of flakes of painted surface.

The face was then reconstructed using the Japanese tissue paper and BEVA backing technique, along with occasional tacks of the acrylic copolymer Paraloid B-72 along join edges. The vulture headdress and sides of the face were attached directly to the head. The central portion of the face was assembled as a separate unit, which required casting “facing” and “backing” supports that conformed to the contours of the face so that it could be safely inverted to work on the interior surface.

PAHMA 6-20106 during reconstruction in the gallery.

PAHMA 6-20106 during reconstruction in the gallery.

After all of the extant fragments had been reassembled, a number of gaps in the face remained.

PAHMA 6-20106 during treatment, after of reassembly of the face.

In order to stabilize the fragile reassembled mask, the larger gaps were filled with a lightweight mixture of 5% Klucel G in ethanol bulked with approximately 1:1 glass microballoons and Whatman cellulose powder. The fills were painted with acrylic paints in order to decrease the contrast between the white fill material and surrounding surfaces.

PAHMA 6-20106, face after treatment.

A storage mount made out of archival materials like ethafoam (polyethylene foam) and Tyvek (smooth spunbonded olefin fabric) supports the mask and allows it to be moved without direct handling.

Tagged
2011 12 08 Cartonnage
Conservation treatments
Live in the gallery
Mummies and mummification Comments (1) Permalink

Put a bird on it

Or rather, put a bird back on it. Reattaching the carved wooden bird to the lid of this Ptolemaic canopic box (receptacle for mummified organs) constituted one phase of the box’s conservation treatment. The other main phase of treatment involved stabilizing the flaking painted surfaces so that the box could be safely handled, studied and displayed.

PAHMA 6-21008. Painted wooden canopic box, lid and bird figurine before treatment.

Carved and painted wooden falcon before treatment, PAHMA 6-21008

The box was collected by British papyrologists Grenfell and Hunt, who conducted excavations on behalf Phoebe A. Hearst and the University of California at Tebtunis in 1899 and 1900. It is thought to represent a shrine, with one wall depicting a set of double doors, and other walls portraying funerary deities and symbols. The bird figurine that sat atop the lid represents a mummified falcon associated with the god Sokar. There are similar canopic boxes at the British Museum and Boston Museum of Fine Arts. PAHMA’s box has been treated at least once before, based on the presence of modern adhesive in a repair and an unidentified coating on much of the painted surface.

Before treatment views of exterior side walls of PAHMA 6-21008. The walls are painted with funerary iconography (Imsety and Hapi, Djed pillar, Duamutef, shrine doors).

The separately carved box elements were attached to each other via wooden dowels, and two loose dowels were found in the box’s interior.

Interior of box (PAHMA 6-21008) before treatment. Loose dowels, drips of ancient residue, and modern restoration materials are visible.

The exterior surfaces were smoothed with a calcium carbonate-based preparatory layer before being painted. The painted ground had detached from the underlying wood throughout the wall surfaces, obliterating parts of the design. In many areas where the painted ground was intact, it was separating from the wood below, threatening to flake off and cause further destruction of the imagery.

Lifting painted ground on the back of the bird figure, proper left side, PAHMA 6-21008.

In order to prevent continued loss of the painted surface, lifting flakes were consolidated, or secured to the wood below with a dilute adhesive.  A 3% solution of methyl cellulose, a cellulose ether, in 1:1 deionized water and ethanol was used to consolidate the flaking surface. By introducing small amounts of consolidant to the undersides of the lifting flakes with a fine brush, I was able to relax the painted ground and reattach it to the wood.

Consolidated painted surface on the back of the bird figure, proper left side, PAHMA 6-21008.

After surfaces on the bird and on the box walls had been consolidated, the bird was reattached to the top of the lid. One of the loose dowels originally found in the interior of the box (see above) fit the hole in the underside of the falcon’s base and the central hole in the top of the lid. A strip of surface down the longer axis of the lid fluoresced differently in long-wave UV light than surrounding surfaces, suggesting that the bird had been attached in that orientation when a coating was applied to the lid during an earlier restoration campaign.

Top of the lid of canopic box PAHMA 6-21008 in long-wave UV. There appears to be an uncoated strip of surface down the center of the lid.

These clues and comparison to similar boxes suggested that the bird was originally oriented facing the box wall decorated with the double doors. Using the peg found in the interior, the bird was reattached to the lid in this position. A foam support was created to pad the underside of the lid, and the lid was replaced on the box to illustrate how it would have originally appeared.

PAHMA 6-21008 after treatment.

Put a bird on it!

 

2011 08 30 Conservation treatments
Painted wood Comments (0) Permalink

Coinacopia!

Coins, coins, coins. So far, the conservation lab has treated eight copper alloy coins this season, most of which were found in a single trench at Poggio Colla.

Coins can provide chronological information about the contexts in which they were found. Being able to identify (and thus date) a coin depends in part on being able to see the design elements on its surfaces. Dirt and corrosion usually obscure these features, which where the conservators come in.

Coin from trench PC 45 before treatment. Burial dirt completely obscures the surfaces. Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

Coin cleaning is a delicate operation. Often the surface in which design features are preserved is very thin and fragile. We use a binocular microscope and various tools to remove material from this surface without disrupting it, revealing the images on the surface without damaging the fragile patina.

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MVAP conservation field school student Carly Hoey treats a copper alloy coin with the aid of a binocular microscope. Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

Characters are revealed on a coin’s surface during cleaning. This type of legend tells us where the coin was minted. Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

Coin from trench PC 45 after treatment. The same surface pictured at the top of the post, after cleaning. Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

After coins have been cleaned and stabilized, we craft small storage supports for them place them in sealed containers with silica gel, a desiccating (drying) agent. Storage in a dry microenvironment slows the metal corrosion process, helping to preserve the coins.

Tagged
2011 07 24 Conservation treatments
In the field
Metals Comments (0) Permalink

Mystery materials

“What is this?”

We get that question a lot. Trench supervisors and students bring unidentified finds down from the field for closer examination in the conservation lab. With help from tools like a binocular microscope, we are able to observe diagnostic features and characterize materials.

This one stumped us for a little while though:

One exterior surface of the "mystery find." Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

Another view of the exterior surface of the "mystery find." Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

Break edge revealing the interior of the "mystery find." Courtesy of the Mugello Valley Archaeological Project: Poggio Colla.

The combination of serrated edges, asymmetrical curvature, one flat side and one convex side, and clear differentiation between an inner “core” and darker outer layer was…weird.

A stone blade? Glass ornament? Ceramic even? These were all suggested, but nothing quite added up. Then one of our knowledgeable colleagues suggested something else.

A fossilized shark’s tooth! We checked some comparanda online, and found that fossilized shark teeth do indeed exhibit all of the strange features mentioned above. You never know what will turn up out here, and we will now be able to identify fossilized shark teeth right off the bat in the future.

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2011 07 17 In the field Comments (0) Permalink

Hello Kitty

In the MVAP conservation lab, we spend a lot of time cleaning excavated finds, carefully removing dirt (and sometimes alteration products) from objects. We clean the finds in order to reveal their forms and surfaces, and to remove material that could cause deterioration. Cleaning is an invasive and permanent action, so we select methods appropriate for the type of object to be cleaned, and work slowly and carefully.

MVAP field school conservation student Emily Ricketts uses a binocular microscope while cleaning a find. Courtesy of the Mugello Valley Archaeological Project.

As we clean, we are very careful to only remove only what we want to remove, primarily dirt. We want to ensure that we don’t remove original material like pigment, glazes, or gilding, or evidence of how something was used, like ancient residues or signs of associated organic materials such as wood or textiles.

Last week, cleaning this ceramic sherd revealed a surprise.

Bucchero sherd from trench PC 41, before treatment. Courtesy of the Mugello Valley Archaeological Project.

As I carefully reduced the dirt sticking to the surfaces of the sherd, the partially obscured incised design emerged. The sherd has a depiction of a feline, perhaps a spotted leopard, unlike anything found at this site!

Hello kitty! Partially cleaned bucchero sherd from trench PC 41, during treatment. Cleaning the sherd revealed a charming feline face. Courtesy of the Mugello Valley Archaeological Project.

Now that the sherd has been cleaned and the design is visible, the find will be studied by the team’s Bucchero specialist and drawn by the professional illustrator.

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2011 07 10 Ceramics
Conservation treatments
In the field Comments (0) Permalink

Field dispatch: reporting for duty

Curious about what happens to archaeological objects before they enter a museum collection? Over the next month I will be blogging from Vespignano, Italy, sharing how the conservation team at MVAP’s Poggio Colla dig cares for recently excavated artifacts. Poggio Colla is a 7th-2nd century BCE Etruscan site, located about an hour outside of Florence. The project is a field school where students learn about all aspects of excavation, including archaeological conservation.

Upon arrival, we began by setting up a field conservation laboratory at Guardia, a farmhouse not far from the site. Finds are brought here for cleaning, stabilization and rehousing.

 

The doors to the Poggio Colla conservation laboratory at Guardia. Courtesy of the Mugello Valley Archaeological Project.

Once the lab was set up, we began to tackle objects from the end of the 2010 season. Thus far we’ve treated metal items and a lot of ceramics, including many Bucchero pieces. Bucchero is a distinctive dark grey Etruscan ceramic fabric, sometimes decorated with stamped and incised decoration.

MVAP conservation interns at work

Pre-program conservation interns and Poggio Colla Field School alums Morgan Burgess and Avery Bayard at work in the lab, cleaning Bucchero sherds. Courtesy of the Mugello Valley Archaeological Project.

 

Pre-program conservation intern Avery inspects a ceramic spindle whorl in the lab. Courtesy of the Mugello Valley Archaeological Project.

We can’t wait to see what emerges from the dirt in week two!

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2011 07 02 Conservation treatments
In the field Comments (0) Permalink

We’re hooked: Preliminary CT results for crocodile mummy PAHMA 5-513

Cut-through rendering of PAHMA 5-513, created by eHuman Inc. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using a Siemens SOMATOM Definition, Siemens Healthcare.

By CT scanning PAHMA 5-513, an unwrapped mummy group composed of an adult Nile crocodile with juvenile crocodiles massed on its back, we learned more about how the adult and baby crocodiles lived, died and were mummified.

We hoped that imaging the interior of the mummy group would reveal if the adult had been eviscerated (had its entrails removed) as part of the mummification process, how the crocodiles died, the gender of the large crocodile, and other surprises. Like wrapped crocodile mummy PAHMA 6-20100, 5-513 underwent two sets of scans at Stanford University. First we scanned the mummy with a clinical CT scanner to identify features of potential interest, and then followed up with high resolution scans using the C-arm scanner in the lab of Dr. Rebecca Fahrig, Department of Radiology, Stanford University

PAHMA 5-513 awaits CT scanning in Dr. Rebecca Fahrig’s lab, Stanford University.

The last supper?

No signs of blunt force trauma were visible on the cranium, vertebrae and other bones, ruling out some modes of death. The CT scans also revealed intact organs, indicating that the adult crocodile had not been eviscerated.  One of the organs visible in the CT renderings is a full stomach. The crocodile’s stomach contains the bones of small prey, round radiopaque objects that appear to be rocks, and a manmade object…

Cut-through rendering of PAHMA 5-513 with dense, radiopaque material visible in stomach. Created by eHuman Inc. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using a Siemens SOMATOM Definition, Siemens Healthcare.

Initially, the concentration of round dense objects in the stomach was slightly puzzling. However, it turns out that crocodilians actually consume stones that remain in their stomachs. The stones help to crush and grind food, which crocodiles do not chew. Acidic stomach fluids also break down the food chemically. Biologists believe that the ingestion of stones may have a secondary function as well, providing additional weight that aids the crocodile in floating just below the surface of the water.

Many small animal bones are mixed in with the rocks.

Fish skeletons in the stomach of PAHMA 5-513. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using an Axiom Artis dTA with DynaCT, Siemens Healthcare. Created using High Definition Volume Rendering® software by Fovia, Inc.

Claw (?) bones of an unidentified animal in the stomach of PAHMA 5-513. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using an Axiom Artis dTA with DynaCT, Siemens Healthcare. Created using High Definition Volume Rendering® software by Fovia, Inc.

The high resolution scans performed at Dr. Fahrig’s lab revealed a final surprise in the crocodile’s stomach. Amidst all the bones and the rocks, there is a metal hook.

Stomach contents of PAHMA 5-513, with radiopaque metal hook (shown in yellow) and round objects that appear to be rocks. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using an Axiom Artis dTA with DynaCT, Siemens Healthcare. Created using High Definition Volume Rendering® software by Fovia, Inc.

The J-shaped hook, with a barbed tip and eyelet, resembles fish hooks from Greco-Roman Egypt. The compact surface and lack of voluminous corrosion products suggest that the hook may be made of a copper alloy rather than of iron.

How did the hook end up in the crocodile’s stomach? Based on its location inside of the stomach and proximity to fish skeletons, the hook may have been lodged in a fish consumed by the crocodile shortly before its death.

The hook may also have been deposited inside of the crocodile during mummification. At the 2011 AIC conservation conference, a conservator from the Field Museum shared CT images of a Ptolemaic period gazelle mummy. There is a very similar metal hook in the gazelle’s hindquarters, suggesting that such hooks were used by embalmers in the course of animal mummy preparation.

5th century BC Greek writer Herodotus offers yet another possible scenario. His Histories includes a section on Egyptian customs, including crocodile worship and mummification, and techniques for capturing and dispatching the dangerous beasts. Herodotus claims that the Egyptians had numerous ways of catching crocodiles, and details one method that involves luring a crocodile out of the water with bait on a hook:

They bait a hook with a chine of pork and let it float out into midstream, and at the same time, standing on the bank, beat a live pig to make it squeal. The crocodile makes a rush towards the squealing pig, encounters the bait, gulps it down, and is hauled out of the water. The first thing the huntsman does when he has got the beast on land is to plaster its eyes with mud; this done, it is dispatched easily enough-but without this precaution it will give a lot of trouble.

(trans. de Sélincourt, 1954)

Of course we can’t know exactly how the hook ended up in the stomach of the mummified crocodile, but it’s fun to imagine a Herodotean turn of events!

Many thanks to Dr. Rebecca Fahrig (Stanford University), eHuman Inc., and Shay Kilby of Fovia, Inc. for their assistance with scanning the mummy and rendering images!