Laser training for our monumental projects team

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.

A small Egyptian limestone stela mid-treatment. Many cleaning tests were carried out on this piece with very little success in removing some of the grime and stains. It is a good candidate for some laser cleaning tests.

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.

Adam demonstrating use of the laser

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!

CLA conservation technician Kyle Norris testing the laser on an Egyptian stela

Special Photography for Larger Objects: Photogrammetry

By Christy Ching

Conservation Technician Christy Ching photographing the underside of an Egyptian coffin 2017-20-1.3 for photogrammetry.

One project I have really enjoyed working on as a pre-program conservation technician is documenting larger objects for a process called photogrammetry. Photogrammetry is a technology that gathers spatial and color information of an object from multiple photographs to form a geometrically corrected, highly detailed, stitched image called an orthomosaic. Essentially, photogrammetry creates a distortion-free, three-dimensional model of an object based on two-dimensional photos of every surface photographed in sections. 

Left: Four photographs of an ancient Egyptian coffin lid L-55-16B at various angles, which were used to create a 3-D model. Right: 3-D model draft of L-55-16B.

*L-55-16B (21-46-9) is a loan object from the Philadelphia Museum of Art (PMA)

This can be done for objects of any size. However, we are mostly reserving this technique for larger objects, specifically larger textiles and Egyptian coffins. This is because photographing the coffins and textiles normally with a single shot requires a greater distance between the object and the camera in order to fit the entirety of the object into the frame, and doing so reduces the image quality. Not only that, but the camera distortion that is inherent in all photographs will become more obvious. The resulting image will not be an accurate representation of the coffin or textile, which is not ideal for documentation purposes. 

The image on the left is a single-shot photograph of L-55-16B while the image on the right depicts the same coffin lid created by photogrammetry. When comparing the two images, the camera distortion in the single-shot photograph can be seen especially in the feet and head of the coffin lid.

With photogrammetry, we can take parts of the 3-D model and use them as high resolution, distortion-free, 2-D images of the object instead.

Six views of L-55-16B depicting the top, interior, and the four sides of the coffin lid generated using photogrammetry.

So far, a little less than ten coffins, a few textiles, a pithos fragment, and a giant granite relief have been documented using photogrammetry. The models and orthomosaic images are all generated by Jason Herrmann from CAAM, and we are very grateful that he is doing this for us! To learn a little bit more about the photogrammetry process, view this Digital Daily Dig here.

This project was made possible in part by the Institute of Museum and Library Services.

An Ivory Figure from Hierakonpolis: Part II

By Tessa de Alarcon

E4893 before treatment

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.

E4893 during treatment: both images show the object during fill removal.

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.

E4893 During treatment: after the break edges were cleaned. The red arrows point to the part of the object which determines the size of the fill as it fits into the break edge of the top half of the object.

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.

E4893 during treatment on the left is the first attempt at filling the loss with the object resting flat. The image on the right shows the object during the second attempt using a foam support system inspired by the rigging at CLA.

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.

E4893 during treatment images showing the final system used to support the fragments during placement of the fill material. The image on the left shows the back during fitting and on the right is a view of the front after placement of 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.

E4893 during treatment. The image on the left shows the object with the fill dry fit into place (no adhesive had been applied yet). The middle and left images show the object after the fill was adhered in place and the gaps filled.

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.

E4893 After treatment

This project was made possible in part by the Institute of Museum and Library Services

The Stories We Wear

By Debra Breslin

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.

SILK

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. 

Deel (garment), Mongolia, early 19th century
Silk, cotton, brass
2002-15-1

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.

SILVER

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. 

Hair ornaments (20452, 20447, 20453, 20455A) in the fume hood

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.

Before Treatment
20448B
After Treatment

GOLD

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. 

Before Treatment
Diadem (Crown), Maikop, Republic of Adygea, Russia, 4th century BCE
Gold
30-33-5

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).

Detail of repair on right side petal
After Treatment

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.

Weapon, Gilbert Islands, 19th century
2003-32-338

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.

Before (top row) and after treatment (bottom row) P3157A

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.

Respecting human remains: edits to past blog posts

In early 2020, we (the Conservation Department) began working on a human remains policy for our department. Our intention was to formalize some of the unwritten rules we have been following and to establish clear guidance for our work and interaction with human remains in the Penn Museum’s collection. Working on and implementing this policy, and regularly revisiting it, will help us to care more sensitively and ethically for these remains with respect for the individual people and also with respect for others who may come into contact with them.

One of the first things we decided is that we would no longer share images of human remains on the internet in any location. Anyone who has followed our blog since it was established in 2012 will know that this is a departure from our previous practices, which included writing posts and sharing images about our work on the ancient Egyptian mummified human individuals in the Artifact Lab. So in addition to no longer sharing such images, we are working on editing our blog and removing, cropping, or blurring images that include human remains. This is not an effort to erase our past practices, but rather an acknowledgement that our feelings on this issue have changed and we no longer support sharing these images publicly.

Another practice we established that affects the blog is that we no longer use the term “mummy” and instead use “mummified human individuals” to refer to Ancient Egyptian people whose bodies were preserved for the afterlife. We have always referred to these individuals by name if known, and we continue this practice. In our experience working in public view and speaking to visitors about our work, we have found that the word “mummy” results in objectifying these people, causes confusion, and creates an unintended emotional distance from them as human beings.

We have many images of human remains on this blog and we have used the term “mummy” countless times to refer to mummified human individuals. We are in the process of making changes to the language and photographs on the blog, while attempting to retain the content as much as possible. We are archiving all original posts for our internal records. During this time we may hide some posts from public view so that we can properly edit them. We appreciate your patience as we carry out this work and we welcome questions and comments. Finally, while most of the content we are editing relates to ancient Egyptian human remains, as that was an early focus of the Artifact Lab, we intend to apply our policies to all human remains, regardless of culture, origin, or time period.

We are grateful to our colleagues who organized and participated in the discussion panel Your Mummies, Their Ancestors? Caring for and About Ancient Egyptian Human Remains on August 18, 2020, which covered this topic extensively and helped shape our discussions as we developed our policy. This panel was co-organized by objects conservator Charlotte Parent, who recently published an article in the April – May 2021 issue of News in Conservation and offers thoughtful perspectives for conservators and museum professionals who work with the remains of ancient Egyptian individuals.

An update on Kaipure’s funerary chapel

By Jessica Betz Abel and Julia Commander

Greeting everyone – there’s a lot to update on from our Conservation Lab Annex (CLA) but for this post, we’re going to focus on the recent progress of Kaipure’s Funerary Chapel. It has been a while since we posted about Kaipure, in fact the last time we posted was almost exactly three years ago. As a quick reminder, two of the walls (the south and east) from the chapel were most recently on display in the Lower Egyptian Galleries, but they were disassembled and deinstalled in 2015 as a precautionary measure due to nearby construction. This also allowed us to proceed with much needed treatment of the flaking limestone and paint as well as designing a new support system in anticipation the entire chapel being reassembled in the new Ancient Egypt and Nubia Galleries. The complete chapel has not been on display in over 25 years!

Here at CLA we are working on building one of the smaller walls as a proof of concept for our engineering team. The south wall is the smallest section and so that is where we decided to start. But before we could begin, we had to locate all the blocks and bring them down from the rafters. 

Julia Commander using the forklift to retrieve blocks from the south wall of Kaipure.

With all the blocks needed for the south wall, we started by erecting the bottom course of stones. Once those were in place and shored up with temporary wood and foam pegs, we laid the first stretcher course on top.

The first two courses of the Kaipure chapel south wall.

In antiquity stones would have been assembled using a mortar, however, using a mortar in an indoor gallery setting is not necessary or practical. Mortars require quite a bit of water for application and that could potentially mobilize any lingering salts in the limestone which could compromise the structural integrity of the stone. Mortar is also much less reversible than many of our other options, not to mention the mess it would create during installation. Instead, we have been investigating interfaces of various materials that would replace the need for mortar or adhesive at all. For Kaipure, we have narrowed down our options to Silicone Rubber and Sorbothane. Both materials have good viscoelastic properties, reduce point loading, distributing the weight of the stones, and providing a grippy material between each course to lock the stones together.

Comparing the working properties of Sorbothane vs. Silicone Rubber.

In addition to the interfaces, we are currently working with our project engineers to design an armature on which each wall can be assembled. The armature will provide the stability and support that many of the individual stones need. In order to not cause any further damage to the stone, we are opting to use the existing holes which were drilled into the backs and sides of the stones during a previous installation. Though we are still very much in the early stages of design we are excited by the prospect of seeing the entire chapel reunited in a few short years!

An Ivory Figure from Hierakonpolis

By Tessa de Alarcon

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.

Before Treatment photograph of E4893

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.

Annotated before treatment photograph of E4893 indicating the large fill at the waist of the figure.

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.

Before treatment photograph of E4893 (left) and an X-ray radiograph of the object (right). The X-ray was captured at 60kV, and 6mA for 6 seconds. There are four nails visible in the fill.

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.

This project was made possible in part by the Institute of Museum and Library Services

IMLS? What’s that?

by Lynn Grant, Head Conservator

If you don’t work in the Museum or Library field, you may never heard the initials, ‘IMLS’. But to many in those fields, it’s a lifeline and important source of support and information. In 2019, the latest year with information, the Institute of Museum and Library Services (IMLS) awarded $223.5 million through grantmaking, research and policy development, to advance, support, and empower America’s museums, libraries, and related organizations. The Penn Museum has received support from the IMLS on many occasions.

Coffin lid of Djed-Hapi (E3413A)

In 2015/16, the Museum moved its Egyptian Collections off-site in order to protect it from vibrations associated with the construction of a large building right beside us. This gave us the opportunity to carry out an inventory and examine the objects in storage to determine which needed conservation. But it’s a huge project; we had originally believed the collection was 42,000 artifacts; it turned out to be more like 50,000. In order to fund such a massive undertaking, we break it down into manageable chunks. In 2019, the IMLS awarded the Museum $250,000 to fund the conservation of a group of Egyptian and Nubian coffins and related funerary goods. This enabled us to have two project conservators dedicated to this group of artifacts, as well hiring two conservation technicians to photograph items for the public database. Despite the pandemic, we’ve been working away at this since October 2019 and will complete the work by the end of September. Over the next few months, the project conservators will be sharing some of their work with you. Enjoy!

Confidentially, not so much

Hi everyone. Lynn Grant, Head Conservator here. Last fall, with a certain amount of hoopla, we started a series called ‘Conservation Confidential‘ which was a once-weekly version of the Digital Daily Dig. Well, it was fun but it was a lot more work than we’d expected and we’re already operating at reduced capacity thanks to the need for distancing. Also, we got very few questions. So, in this new year, we’ll be doing the Conservation Confidential on the last Friday of each month (Final Friday). In the meantime, we’ll try to be more proactive about blog posts and will seek other ways to connect with our virtual and on-site visitors (The Museum reopens this Friday) As always, if you want to chat with the conservators, use the Ask Us link in this blog.

A Puzzle without all the Pieces: Treating Papyri

By Jessica Byler

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.

Left: Removing papyrus (49-11-1) from a Mylar enclosure using an ionizing blower
Right: Using a light box to realign fragments

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.

Temple robbery papyrus (49-11-1), before treatment

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.

Left: detail of the back of the right section before treatment
Right: Section under transmitted light from a light box, with red arrows pointing to the two fragments in the wrong spot

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.

Left: Detail of front, with red arrows pointing to ink which does not meet up
Right: Detail under transmitted light, with red arrows showing that the fibers do not line up

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.

Left: Detail of back during treatment, with the two fragments, indicated with red arrows, properly aligned
Right: Detail of back during treatment, with red arrows pointing the two fragments, and blue arrows pointing to some of the new bridges; areas of white residue from the old materials is also visible

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!

Temple robbery papyrus (49-11-1), after treatment

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).