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

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.

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

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).

Conservation Confidential: Tools galore!

Today’s Conservation Confidential, Tools of Every Trade: Conservation Ingenuity with conservator Lynn Grant can be viewed at vimeo.com/483259426. You can also catch up with others in this series by looking in the Conservation Confidential section at https://www.penn.museum/events/adult-programs/the-daily-dig. Many of today’s stories and images were drawn from our 8 years of Artifact Lab blogging. If you want to know more, here are links to the relevant posts:

  • Molly’s tools:  https://www.penn.museum/sites/artifactlab/2015/08/17/the-right-tools-for-the-job/
  • Gel Cleaning: https://www.penn.museum/sites/artifactlab/2017/12/08/coming-clean/
  • Restringing: https://www.penn.museum/sites/artifactlab/2018/05/16/beaded-necklaces-restringing-to-secure-the-past/
  • Kitchenwares: https://www.penn.museum/sites/artifactlab/2017/04/11/cleaning-questions-and-cross-sections/
  • https://www.penn.museum/sites/artifactlab/2017/12/08/coming-clean/
  • https://www.penn.museum/sites/artifactlab/2013/01/10/making-scarab-amulet-impressions-part-2/

Cuneiform Conservation Conundrum

Image

One of the earliest known forms of writing is cuneiform, a wedge-shaped script developed by the Sumerians, around 5000 years ago. It is preserved on stone carvings and clay tablets. The survival of the clay tablets is amazing, given that most were of unbaked clay – essentially mud. Today’s Conservation Confidential (1 pm EST on Penn Museum’s Facebook page) will feature conservator Tessa de Alarcon discussing the preservation of these earliest written records.

The right tools for the (monumental) job

Greetings from the Penn Museum’s Conservation Lab Annex (CLA)! You may remember from our first post the scale (large!) and types of objects we are going to be working on over the next few years. We are mostly working on architectural elements like doorways, windows, and columns that were part of the palace complex of the Pharaoh Merenptah, who ruled Egypt from Memphis from 1213–1203 BC. To put things in perspective, the doorway we are currently working on is over 12 ft tall and many of its fragments weigh hundreds of pounds. That means we have had to add a few new tools that are not typically found in a museum’s conservation lab. Most recently we’ve started utilizing a lot of new tools including a forklift, a gantry, and large-scale sandboxes.  

  • Forklift – A few weeks ago, the whole Ancient Egypt and Nubia Galleries Team attended a certification workshop in forklift operation. The certification course taught us the basics in how to safely operate our electric forklift. Having our own forklift onsite allows us to easily move some of the large stone fragments in and out of the lab, reorganize the layout of the warehouse to create space for rigging and lifting, and organize all of the Merenptah Palace pieces into one area.   
Egyptian Section Curator Dr. Jennifer Wegner smoothly maneuvering the forklift during our training session.
  • Gantry – At CLA we have a gantry crane in the warehouse which allows us to rig and lift some of the heaviest objects and fragments. This is especially important when we are trying to dry-fit pieces together before making more permanent joins. There are lots of different ways to rig or strap a fragment for lifting, but we’ve found that using shorter straps with a choke hitch is the safest way to lift our artifacts. In the photo below you can see that’s exactly what we’ve done. Once we have the straps secured and fully supporting the object, we begin to slowly lift, making sure the straps settle and don’t slip or re-adjust, dropping the object.  
CLA team using the gantry to lift part of the lintel from Doorway 1.
  • Sandbox – Sandboxes are often used in conservation to support objects during joining. Using a sandbox, we can place an object inside at whatever angle we need to in order to support the object on top with nothing but the weight of gravity. At CLA, our objects are quite large, so we are using old shipping crates and converting them into large sandboxes to accommodate our needs. In the photos below you can see the process of moving a fragment into the sandbox and then in the second photo you can see that fragment has been placed in such a way that it can now support the weight of the second, joining fragment on top of it. The blue tape serves as a guide to help us know exactly how the two pieces fit together once we have applied the adhesive and are ready to do the final joining. 
CLA team moving part of the lintel from Doorway 1 into a sandbox.
Fragments of Doorway 1 lintel being dry-fit together in the sandbox prior to joining.
  • Dremel – Lastly, and on a much smaller scale, we’ve been using a few different power tools. The most helpful so far has been the Dremel. While the Dremel is not a completely foreign tool to many conservators, it is most often used for making mounts or sanding fills and/or cross-sections. In this case we are using the Dremel to cut and remove all restoration pins that have become heavily corroded over the years, expanded, and are causing damage to the stone.   
Corroded ferrous pins from a previous restoration being cut and removed from Doorway 1 fragments.

As with any job, having the right tools is really important, for success and safety! We look forward to continuing to share the progress we’ve made on this project from our home offices, as we continue to work from home.

Lessons Learned: You Cannot Treat Dry Wood Like Wet Wood

by Tessa de Alarcon

Documentation of conservation treatments undertaken in the lab is a very important part of what we in the conservation department do at the museum. One of the main reasons we document our treatments is so that conservators in the future don’t have to try to figure out what was done to an object. Instead those future conservators can read our reports and start off knowing the treatment history.  

An array of treatment reports, and log book entries, from the conservation department at the Penn Museum

We are also sometimes those future conservators, looking back at previous treatments. This means that not only can we see an object’s treatment history, we have the opportunity to evaluate and learn from the decisions made by conservators decades ago. Some of these treatments were successful, and some were not. Now we know to avoid those treatments that clearly did not work.

I recently completed a treatment on an object that is a good example of this process. E11151 is a carved wooden figure from Nubia. It was treated before I worked on it by a conservator in the 1970’s. The photo below is how the object looked when it entered the lab at the end of last year.

Before treatment image of E11151 taken in 2019

In the case of this object, it was noted in the 1970’s as having a slightly powdery surface. The conservator conducting the treatment decided to apply a consolidation method that is frequently used on waterlogged wood: immersion in a solution of PEG (polyethylene glycol). PEG treatments are still done today and are very effective at consolidating and stabilizing waterlogged wood before it dries out. But because of this treatment and others done at the museum around this same time period, we have learned that consolidation with PEG is not effective on dry wood, even if it once was waterlogged. E11151 was dry wood and did not come from a waterlogged context.

E11205, E11187, E11203, E11151
E11151 is on the far right.
This publication photo was taken before the object was treated in the 1970’s.

The photo above is a publication photo of the object before it was treated in the 1970’s. While there is no photography with the 1970’s treatment report, there is a sketch which suggests that the object looked similar to this photo when it entered the lab at that time. As you can see there are quite a few differences in the object’s appearance as it entered the lab in 2019 and how it looked before it was treated in the 1970’s.

Before treatment photo of E11151. The red arrow is pointing to an area of thick, white, and hard high molecular weight PEG and the blue arrow is pointing to soft and sticky low molecular weight PEG

Two different molecular weights of PEG were used on this object, a hard high molecular weight one that was used to consolidate the powdery wood and looked white on the surface where it was very thick, and a low molecular weight one that was used to join pieces of the object together and left the surface tacky and sticky. The sticky PEG also trapped a lot of dirt and dust on the surface of the object.

After treatment detail of the top of E11151

The detail above shows the top of the head of the object. The report from the 1970’s states that during treatment the object began to crack and fragment. PEG is typically dissolved in water or ethanol. Both solvents were used in the PEG treatment of this object. These two solvents can be mixed together and during a normal PEG treatment the wet wood starts with PEG in water and then moves to PEG in ethanol: this helps start the drying process. As the waterlogged wood is also already wet, the PEG can penetrate fully into the swollen wood. However, in the case of dry wood, these solvents (ethanol typically has some water in it) introduce moisture into the object, and it starts to swell as wood is very responsive to moisture. It then has to dry out again after the treatment, causing the wood to shrink. This is stressful for the object. This stress is what likely caused the cracking documented in the report and visible in the image above.

E11151, after treatment photo from the treatment completed in 2020

Here you can see what the object looks like now that I have finished my treatment. Consolidation is a very permanent and tricky to reverse treatment, even when adhesives that remain soluble, like PEG, are used. There is currently no way to remove the PEG from this object. All I have done is reduce the PEG on the surface by cleaning it with ethanol. I also used the previous documentation to figure out where small detached fragments went so that it looks more like it did originally. While the treatment that was undertaken in the 1970’s seems to be over-treatment as it caused new problems, some more severe than the problems the object had to begin with, I do also want to recognize that it is because of past experiments like this one that I know not to use PEG on dry wood.

Because wholesale consolidation is a fairly permanent and risky treatment, I think long and hard when I choose a consolidant. I also remain aware that there is a chance that someday, some future conservator, will deem some of my treatments mistakes as well. Hopefully my mistakes will be ones that they can learn from too.

To learn more about PEG treatments for waterlogged organic materials, check out these links:

Ellen Carrlee Conservation blog: High Molecular Weight PEG for basketry

Queen Anne’s Revenge blog: Waterlogged wood – Gotta bulk it up!

Cardiff University Conservation: Newport Ship Workshop

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