“Technical analysis” is a term frequently used in the conservation field to describe the use of specialized techniques to examine objects. Those techniques can include using scientific instruments, special cameras, and lots of other equipment. Maybe that term sounds boring, but in addition to telling you a lot about an object, you can also sometimes find fun surprises.
This was certainly the case when I began some preliminary analysis on an alabaster bowl for the reinstallation of the Egyptian and Nubian galleries. The bowl dates from the Egyptian Early Dynastic period, from roughly 3000-2800 BCE.
Before starting what was seemingly a simple treatment of retouching/repainting some old fills, I assessed it under ultraviolet (UV) light in a dark room. My goal was to take a look at the fills and adhesives, hoping that UV would give me some information about the materials used. When I turned off the UV light, I noticed a faint greenish glow coming from the bowl. It looked like a glow-in-the-dark sticker.
Trying this a few more times verified that I wasn’t imagining things, and the light was coming from the alabaster bowl itself. For a second or two after I turned off the UV light, the alabaster would glow. A bit of quick research taught me that this phenomenon is called phosphorescence, and does, indeed, occur in alabaster.
Phosphorescence is a type of photoluminescence; the higher energy UV light is absorbed by the material and emitted at a lower energy (in the visible range). Unlike fluorescence, which occurs only while the light is applied, phosphorescence continues for a longer period of time, from a few microseconds to even hours.
This glow-in-the-dark quality is usually not noticeable because even if there is enough UV to cause phosphorescence, the result is so dim that it gets easily overpowered in the presence of visible light.
What does this finding have to do with planning my simple inpainting treatment? Absolutely nothing, but those are often the most interesting finds. While the inpainting treatment did not specifically benefit from this find, this knowledge can be applied in other ways, like identifying alabaster before turning to more intensive methods. Discovering phosphorescence in alabaster artifacts is a reminder of the many surprises that can be uncovered through the process of technical analysis–and that technical analysis, which might sound dry, is often how we find the most interesting things.
We’ve had a few posts (this one by Chelsea Kim and this one by Christy Ching) on creating 3D models using photogrammetry, and I thought I’d give some examples of what we are doing with that data once it’s collected. For some objects we are creating ortho-mosaics and these 2D images are going into reports as after treatment images as well as going into the catalogue model as record photography that also shows up in the online collection database. This wooden coffin 2017-20-1.3 is an example of this type of imaging.
For other objects we are also producing ortho-mosaics, but they are before treatment images. For example with E641 a wall painting that was previously on display.
The wall painting is currently in two sections and each one has been imaged separately. These before treatment images have been used to create condition maps.
The maps go into our reports and help provide visual documentation to support our written reports. For large objects, these kinds of condition maps are often easier to understand than written descriptions and can provide more precise information on the location of specific condition issues. Here you can see the condition map for E641. The map is not yet complete, I am still working on documenting one of the sections but I have combined the two maps into one image so you can see what that process looks like.
The models can also be used to show surface distortion, so here in this screen shot of the 3D model of E641 you can see planar distortions in the wall painting where the fragments are not aligned. There may be a variety of causes leading to this distortion including poor alignment during the previous reconstruction or they may be the result of lifting/separation of the original material from its current modern backing.
I am currently working on learning how to create a 2D false color image where the colors reflect depth, so that we can have these planar distortions documented in 2D as well as being able to see them in the model.
So all together, this data is being used to document both the final condition of objects after treatment, as well as to document them before treatment. The models are also useful tools to assess complex condition issues and are valuable for evaluating next steps. For example, our current plan is to remove the wall painting from it’s current modern backing and put it on a new one. Our hope is to correct some of these planar distortions as a part of that process, and this model as well as one we make after treatment will be useful for evaluating the efficacy of the treatment and provide a base line for assessing its condition in the future.
Typically, at the Penn Museum when we are working on objects, even for display, we prioritize stability over aesthetics. This means that we are often do less cosmetic work than would be done at an art museum when it comes to putting in fills and toning out areas of loss. However, I recently undertook a project where I went further than I usually do to recreate lost material. This blog post is going to walk through why that decision was made in this case as well as some of the mysteries that I found along the way
The object in this case is an Egyptian cartonnage mask E1019. When it entered the lab it had a lot of condition issues, including the top of the head was partially crushed, it had been heavily treated before, and it was missing the inlays for its eyes and eyebrows. The missing eye inlays had been giving many visitors to the lab the creeps as the mask appeared to have dark empty eye sockets. Because of this, from the start I had been polling to my colleagues about what level of repair I should do to reduce the distraction of the missing inlays. I was not at this point considering replacing them, but was instead thinking about maybe toning out some of the other losses on the cheek to draw less attention to the eyes.
When it first entered the lab the mask was being tracked as E17632 but over the course of the treatment, I found a different accession number on the interior, E1019. With the help of our curators, we were able to piece together that E1019 was the original accession number, and E17632 had been assigned to it later. When I looked up the record for E1019 in the museum collection database, I found the record included two eye inlays! I was so hopeful that this would mean that I could reintegrate two inlays, one into each eye. However, when I reached out to the curators to get more information, I found out that they are two parts of the same eye, the white part of the eye and a pupil/iris.
Well, this left a new set of problems. Especially since you can see here, the white part of the eye was not very white anymore since it was covered with a dark brown substance. I was left with a lot of options, leave the eye inlays out, reintegrate them as they are, or clean them and reintegrate them, and if I reintegrated them should I then also create a replica set for the other eye?
Before making any decisions, I checked to see if they inlays fit the eye sockets in the mask, which they did. The inlays turned out to be for the masks right eye. After that, I spent some time characterizing the dark coating on the white part of the eye inlay. This included UV examination and comparing how the coating fluoresced with the brown modern materials I found on the interior of the mask from previous treatments. The results were not as clear cut as I was hoping. It seems that there is more than one brown substance on the inlay based on the UV examination. With this data in hand, I reached out again to the curators with the options of leaving the eyes out, reintegrating them as is, or cleaning and reintegrating. The curators indicated that they wanted the inlay reintegrated, and that they would like a replica for the missing inlay as well so that she looked even as one eye seemed worse than no eyes. Together we decided to clean the eye inlay, but to keep samples of the substances on the inlay for future analysis.
Once clean, I set about making a copy for the masks left eye to be a close but not identical match. Based on previous experience I decided to make the new inlay set out of a two-part light weight epoxy called Wood Epox as it is easy to shape and can be sanded and carved. To start, I made a paper template of the shape of each inlay. I made sure to mark what I wanted to be the front of each so that the shape would be a mirror image of the original inlay. The white inlay is slightly curved, so I also created a form that would have the same curvature using foam.
Next, I rolled out some sheets of wood epox, and using the paper template trimmed out the shape I needed for both parts of the eye. The pupil/iris part I let set flat, what let the one fore the white of the eye set in the form I had made so that it would have the same curvature as the original. Once cured I sanded them to finish, with the final stages being wet sanding so that the replica inlays would also have a natural gloss.
The final step before assembly and placement in the mask was the paint them to resemble but not exactly match the originals. I used gloss medium for the pupil/iris as this inlay was especially glossy and I could not get that level of gloss with polishing and painting alone.
Finally, here you can see the end results after treatment. You will see though, that I have not attempted to recreate the inlays for the eyebrows. Because we had the one set of eye inlays, I had something to reference for making the replica set of inlays, however, there are still pieces missing which I had no frame of reference for. There were also likely inlays that went around the outside of the eye as well. These and the brows might have been made out of a variety of materials and without the originals for reference, there is no way to be certain about what their color and appearance would have been.
This ancient Egyptian cartonnage funerary mask (L-55-289*) from the late Roman Period came into the conservation lab for treatment as part of the 2021-2022 curriculum internship in the conservation lab. It arrived on a backing board that was not adequately supporting the three-dimensional shape of the piece. The back of the head was the most damaged, and where I did most of the treatment work. I began the treatment by building a mount to support the mask from the front so I could remove the backing board and perform most of the treatment from behind.
*L-55-289 is a loan object from the Philadelphia Museum of Art
I toned Japanese paper using Golden Fluid Acrylics for mending the piece. I applied this paper across almost the entirety of the back of the head using 5% methylcellulose as an adhesive. The mends were applied in pieces: first to re-enforce the linen that remained attached to the mask, then to re-attach fragments back onto the mask. I used Volara and soft tipped clamps to support and maintain the shape as the piece dried.
Once the mask re-gained dimensionality in the back, a new mount was required to adequately support it. I sculped a new mount in two pieces so it could be removed from the object if necessary. The two-piece mount is made of WoodEpox and Ethafoam with wooden skewers to hold the pieces together.
Furthermore, this new storage mount was necessary to hold the piece upright. The piece looks so much better now that the head has been re-formed.
by Tessa de Alarcon with images by Alexis North, Molly Gleeson, and Christy Ching
We recently de-installed two stone sarcophagi from Egypt from the upper Egypt gallery at the Museum: E15415 and E16133. These pieces are slated for reinstall in the new Egyptian and Nubia Galleries and will likely need extensive treatment before they go back on display. This is why they have come off display, so that we can assess their condition and evaluate what needs to be done for the new gallery. For both pieces, we need to check the stability of the previous treatments. Both have previous joins and fills that were done before the formation of the conservation department. This means that we have no records for when these treatments were done or the materials that were used to reconstruct the stone and fill the losses.
In the case of E15415, this meant we needed to see the underside. We brought in Harry Gordon, a sculptor and professional rigger, to build a wooden cradle or cribbing and then lift the piece and flip it so we could see the joins and fills from the other side.
When we flipped the object over and took the plinth it had been sitting on off, we found an additional puzzle. The piece has had a plexiglass vitrine over it for quite many years to protect it while on display. However, that has not always been the case, it used to be uncovered in the gallery. It seems that prior to the placement of the vitrine some visitors took advantage of the small gap between the stone and the wooden plinth below it to slide things under the object.
In a way, this has made this object a sort of time capsule. We found a number of things that had been hidden under the sarcophagus including a coupon for Secret deodorant (worth 5 cents), a program for the Graduation Exercises for the University of Pennsylvania Oral Hygiene Class of 1967, a museum map from the when the museum was called The University Museum, a votive candle donation envelope for the church of St. John the Evangelist Sacred Heart Shrine, a scrap of paper with dishes on it, and two black and white photographs. While some of these things are easily identifiable, like the program and the coupon others are more of a mystery.
I personally find the photos the most interesting. They look like shots perhaps from a photo booth. This is based on their size and format and that each has a torn edge (one at the top and the other at the bottom) suggesting that they may have been part of a longer whole or strip of images. Who is the subject in each image? Were the photos discarded because the owner or owners didn’t like them? Were they taken at an event or party at the Museum? Were the photos captured at the same event or in the same photo booth (if they are indeed from a photo booth)? They are similar in size and format, but that doesn’t mean they relate to one another. Were they taken somewhere else and discarded during a visit to the Museum? I have only questions and no answers, but my hope is that by sharing these images maybe someone reading this will know or recognize them and be willing to tell us more.
Our department has owned a Compact Phoenix Nd:YAG laser for several years now and we have successfully used it to clean objects like this trio of birds for our Middle East Galleries. While there are a lot of possible applications, we have found the laser to be especially effective for cleaning stone objects with coatings, stains, and surface grime that are not easily removed using other tried and true cleaning methods including solvents, steam, and gels.
Did somebody say “stone objects with coatings, stains, and surface grime”? Because we have tons of those (literally) in our Conservation Lab Annex (CLA) where we are working on monumental projects for the Ancient Egypt and Nubia Galleries. But the last time we held a laser training session was before we hired our CLA team. Lasers are not found in all conservation labs, so it is not unusual for experienced conservators to have little to no experience with lasers.
In order to ensure a safe set-up and to get everyone trained on the equipment, we brought in Philadelphia-based conservator Adam Jenkins to provide the team with a full day of training. Adam specializes in laser cleaning and also conducted our last training session at the Museum in 2017.
After a classroom session covering the fundamentals and science of lasers, and the necessary safety protocols and PPE, we moved to the lab to try the laser on a few objects. We had success with several, which is very promising! The team is now set up to continue laser testing and cleaning on their own. We are grateful to Adam for his expertise and support and for this professional development opportunity. We are excited to incorporate this tool into the work out at CLA!
The figure you see here E4893 is an ivory statuette from the site of Hierakonpolis. In a previous blog post I discussed the X-radiography that helped me determine that the large fill around the waist of the object could be safely removed. Based on that X-ray, I was able to mechanically remove the soft fill material and separate it from the object.
Sometimes the full picture is not always clear from an X-ray. While I was able to remove the fill material and the nails, one thing that was not apparent on the X-ray and only became clear during treatment, is that part of the lower half of the object was embedded in the fill. This section also keys into the upper fragment. This may seem like a minor detail, but it is very important for knowing how the pieces should go back together. The loss in the waist is large and a fill is needed to stabilize the object structurally. One worry I had as I approached this treatment, was figuring out what the fill should look like and how elongated should the body be. However, once I found that in the fill there was a section of the object that keyed the bottom and the top pieces together, I knew that the placement of the two fragments could be conclusively determined.
Even knowing how the pieces should go together joining the pieces was far from straight forward. The point of contact is too small for an adhesive join without fill material taking the weight of the fragments or to relay on the connection to hold the pieces in alignment during loss compensation. I had to instead figuring out how to support the fragments in the correct alignment while I created the fill. I decided that the best way forward was to create a removable fill using an epoxy putty. This is a fill that has to be adhered in place, as if it were another fragment, rather than relaying on the fill material to adhere or lock the fragments together. This means that I needed a barrier layer between the fill material and the object, and a system to hold the pieces together. The barrier layer is meant to prevent the fill material from sticking or adhering to the object and you will see in the images below that there is cling film between the epoxy and the object that I used as a barrier layer. The support system, however, took some trail and error before I found a method that worked.
First I tried laying it flat in a bed of glass beads to support the object, but this did not work, it was too hard to see if I had everything lined up correctly and the fragments kept shifting as I put the epoxy in place. Taking inspiration from my colleagues working on Egyptian monumental architecture at the conservation lab annex (CLA). I decided to try making a rigging system in miniature to hold the fragments in place vertically. This allowed me to see the object all the way around and check the alignment more reliably. However, my second attempt using a vertical support system with the object upside down, still led to too much shifting when I tried to put in the fill material.
As a result, I adjusted the system from the second attempt and put the object right side up, carved a chin rest for the figure into the foam support and added a piece of foam to the back to hold the upper fragment more securely in place. The wooden skewers you can see in the images are used to hold the foam pieces together. My third attempt was very effective at holding the object in place in a rigid way with no shifting and gave me plenty of visibility to check the alignment.
After I made the fill, I sanded it smooth and checked to make sure it fit right. Here you can see if dry fit in place and after everything was joined together. This should be a much more reversible treatment than what was done before should this treatment need to be redone again at some point in the future. While the object does not look all that different from the way it did before treatment, it is much more stable now with materials have better aging properties and allow for easier retreatment should that be needed.
This project was made possible in part by the Institute of Museum and Library Services
Over the past 18 months, I completed the examination and treatment of over 200 objects for the upcoming exhibit, The Stories We Wear, which will open at the Penn Museum in September 2021. The exhibit focuses on the idea that what is worn on the body tells a narrative about time, place, and culture. Ethnographic and archaeological material from Oceania, Asia, Africa, Europe, and the Americas will be featured. Alongside these objects will be contemporary ensembles with local connections.
One of the most interesting aspects of treating this group of artifacts is the extensive range of materials. I worked with metals such as gold and silver, fabrics made of silk or wool, organic material such as hair and teeth, and different types of wood. For an objects conservator, this was an ideal project to challenge and enrich my skills. Below are examples of the types of materials that came across my workspace in preparation for the exhibit.
Many of the objects in the exhibit that represent the various cultures of Asia are made of silk. Since silk is a fragile and light-sensitive material, these artifacts will be taken off display after a few months and replaced with similar objects to avoid over-exposure to light in the galleries.
This beautiful silk garment is part of the wardrobe of a married Khalkha Mongolian woman. The silk on the padded shoulders had become worn and thin and was torn at the highest points. These areas were covered with toned Japanese tissue. I toned the tissue with acrylic paints to match the surrounding material and slipped it under the edges of the broken fabric.
Another example of remarkable artifacts from central Asia are these 19th century silver hair ornaments worn by the Daur women of Inner Mongolia. These were used to adorn their elaborate hairstyles. When these pieces came to the lab, they were dark with tarnish, and it was difficult to see their details.
In a museum of archaeology and anthropology, tarnish is not often removed from objects, as it is usually considered part of the historic record of the object. In this case, I talked with the curators of the exhibit and we felt it was appropriate to safely remove the tarnish and coat the silver objects to fully reveal their details.
Many cultures around the world valued gold as a symbol of high status. One of several such objects in the exhibit is this gold diadem. The rosettes are believed to have decorated a headdress or garment of an elite Scythian woman. They were mounted on a modern rod in the 20th century. The rosettes are made of gold foil and wire.
One of the petals of the flower on the far right had broken off at some point and was stored with the object. The petal was attached on the back side with Hollytex fabric (a spunbound polyester) and B-72 (an acrylic copolymer in acetone).
OTHER ORGANIC MATERIALS
In addition to silk artifacts, other objects made of plant and animal materials will be on display, such as this weapon made by the I-Kiribati people of the Gilbert Islands. It is constructed of wood, coconut fiber, and shark teeth.
After cleaning the surface with soft brushes, the shark teeth were further cleaned with enzymes and deionized water. To stabilize loose cords and teeth, I added small pieces of cotton thread through the existing holes. The red circles indicate the areas of added thread.
Here is an example of what the shark teeth looked like before and after cleaning on a small dagger.
These are just a sample of the artifacts that will be on display in The Stories We Wear exhibit opening in September 2021. I hope visitors will appreciate the history and craftsmanship of these objects as much as I do.
The figure you see here, E4893, is an ivory statuette from the site of Hierakonpolis that I am working on as part of an IMLS grant funded project. I have just started the treatment, but thought I would give a brief run through of the initial examination since this is a good example of when and why we use X-radiography in our department to evaluate the condition of objects before treatment.
You may have noticed that the middle of this object is fill, so not part of the object. The fill has some cracks and splits that suggests it is unstable and should be removed. There is no written documentation for when this fill was done or by who, but it’s possible that this was done shortly after it was excavated. The object was accessioned in 1898. Given that the conservation lab at the Penn Museum was not founded until 1966 that leaves a big gap for the possibilities for when this treatment might have been done.
Based on previous experience, I often worry with these old fills that there are unseen things, like metal pins or dowels, lurking below the surface. X-radiography is a great way to check for these types of hidden previous treatment issues. Though in this case, what I found when I X-rayed the object was not your typical pin or dowel.
Here in the X-ray you can see what I found: while this fill did not have any pins or dowels, whoever had done this treatment had decided to reinforce it by putting nails (4 in total) into the fill material. While this makes the figure look like he has eaten a bunch of nails, it is in some ways better news than a pin would be. Pins usually go into the original material, and if they are iron, can rust and expand causing damage to the object. Pin removal can also be risky and lead to damage of the object especially if the pin is deeply imbedded or corroded into place. These nails, on the other hand, appear to be only in the fill and do not look like they go into the original material of the object at all. This suggests that removal of the fill and the nails should be possible without damaging the object. As this treatment progresses, I will follow up with additional posts and updates.
The condition survey of our papyri collection is complete – I counted almost 4,300 fragments of papyrus and vellum, more than we realized were there! The papyrus ranged in size from a few millimeters to 9 feet long. Now, I have moved on to treating a few of the papyri that will be on display in the new Egyptian galleries.
Many of the papyri are sandwiched between pieces of Mylar. Static from Mylar can lift off friable ink or even split the two layers of the papyrus fibers and damage the papyrus. In order to safely remove the papyrus, I use a MinION 2 Ionizing Blower to eliminate the static charge. After removing the papyrus from the Mylar, I can then remove old repairs, realign fragments and fibers that are out of place, and apply new tissue paper bridges. Using a light box can help me identify joins and keep fragments in alignment. Papyrus fibers have different thicknesses, widths, and orientations, so transmitted light from a light box reveals the unique fiber pattern.
Let’s look at one papyrus I am currently treating: a Temple robbery papyrus (49-11-1), dated to the 20th Dynasty or 11th century BCE. Along with removing old materials that might harm or obscure the papyrus, a key reason I am treating this particular document is to make sure the joins are right. It is fragmentary and there have been several treatment campaigns to repair it using a variety of materials, including Scotch tape, Japanese tissue, and Document Repair Tape.
I removed the old repairs where possible and reassessed the location of the fragments. At some point, several of the fragments have become misaligned or detached. In several instances, the fragments were just slightly out of line and could easily be nudged back into place. However, I quickly noticed some issues with a long fragment on the far left (on the right in the photo of the back below), and a small rectangular fragment at the bottom.
On the long fragment, there are ink marks either side of the join which do not meet up. If the fragment was in the correct location, you would expect the writing to extend over the break. On the smaller fragment, the color, curvature, and thickness were different than the surrounding fragments. Using transmitted light, it is clear the fibers of these fragments do not actually line up correctly. Although at first glance they might not look out of place, they clearly do not belong there.
The long fragment has two lines of writing at the top, so the number of locations it could join was limited. The small fragment at the bottom did not have any writing on it, so it was harder to determine its orientation and position. To add to this complicated puzzle, these pieces also might not join to any of the extant fragments.
Thankfully, their proper locations were easy to find using a light box. As you can see in the detail photos above, the fibers of the papyrus were a perfect match. The tissue paper bridges I used were around the size of a grain of rice and are clearly visible but blend in nicely with the papyrus. The Temple robbery papyrus is now ready for display!
This project is funded by the Antiquities Endowment Fund (AEF). The AEF is supported by an endowment established with funds from the United Stated Agency for International Development (USAID).