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 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!

Conservation Confidential: Scaling Up

Check out today’s Conservation Confidential, Scaling Up: Treating Monumental Architecture with Julia Commander, Alice and Herbert Sachs Egyptian Collections Conservator. Get to know the museum’s Conservation Lab Annex and the big things going on there.

You can also catch up with other posts in this series here.

Picture (im)perfect

Hello again from CLA (or at least from our home offices)! As we’ve mentioned before, conservators love to look at records relating to the objects we’re treating. It helps us to gain insights into the artifact’s history and gives us context for what we see on the bench in front of us. While we don’t always have exhaustive information about every single piece, it’s always interesting to do a little research when we can. One of our recent blog posts discussed how we’ve used archaeological renderings to understand traces of colors on our objects; this post will take a look at how photographic records can inform us about the current condition of the pieces.

Photograph of the Penn Museum Archives
A view of the Penn Museum Archives.
Each of these boxes is filled with a treasure trove of information.

Before the CLA team dove into the hands-on work last fall, we took a trip to the museum’s extensive archive collection to do some digging into the history of Merenptah’s palace. With the help of Alex Pezzati, Senior Archivist, we were able to read through the records of the excavation, led by Clarence Fisher from 1915-1920. Our research was also guided by the work of Dr. Kevin Cahail, whose own forays into the archives have revealed a lot of missing details about the site. He was able to provide a lot of insights into what we were seeing in the photographs.

One of the things that impressed us most about the excavation images is the sheer scale of the architecture. While we’re very familiar with our columns and doorways by now, it’s quite another thing to see them in situ. The picture below shows columns and pylons (trapezoidal gateways) from Merenptah’s Coronation Chapel. These objects were previously exhibited at half height because the ceilings in the downstairs gallery were too low, but they’re about 25 feet tall. Part of our project for the new galleries is to figure out how to display these columns at their full height so museum visitors can experience them the way the Egyptians would have. In the meantime, it’s a useful reminder to look at images like this to remind ourselves that they stood for several thousand years!

Site image of the Coronation Chapel during excavation
The Coronation Chapel mostly excavated. The columns would have had capitals, but otherwise are at their full height.

Another thing you might notice in that image is all the water on the ground. The site is in the Nile flood plain and experienced several very wet seasons. We could tell from the current condition of the stone that it had been waterlogged. Stone is often thought of as being hard and unchangeable, but this particular Egyptian limestone contains a lot of clay, so it becomes very soft when wet. Fisher’s notes talk about how fragile the stone was, and ultimately how they made the decision to bring the pieces back to Penn before they deteriorated even more. The stone was still damp when it was wrapped in linen and packed into wooden crates – which explains the fabric impressions we see in the surface of some of the pieces.

Workers preparing columns for shipping and stone with textile impressions
(Left) Workers preparing the column pieces for shipping. (Right) An example of the stone surface with impressions of the textile weave.

Images from the site are incredibly useful tools when we’re looking at damage to an object and trying to determine the cause – whether the damage occurred before excavation or due to more recent changes. They’re also helpful when we’re trying to figure out the extent of old repairs. When the pylon pieces were installed in the gallery in the 1920s, they were extensively restored with plaster and paint. We could also tell that some lost stone had been replaced with bricks and cement, but it was difficult to tell where the restoration ended and the stone began. Fortunately, there were a lot of pictures taken of the coronation chapel while it was being excavated.

Coronation Chapel pylon
(Left) The left pylon during excavation. Notice that the row of figures second from bottom is almost completely lost. (Right) The same object with plaster reconstruction. The detail was based on the other pylon, which is much more intact.

Looking at the original photographs of the left pylon, we could tell that it had already suffered significant surface loss to the bottom and middle sections. We could also see that even though it was still standing, the middle part had broken into several pieces. Using that knowledge during the deinstallation process, we were able to rig around the damaged areas and to remove the old restoration material so the pieces could be separated. When the pylons are reinstalled in the renovated galleries, they will be safely displayed on custom steel support structures. We’re working on how to replicate the decoration, but we’ll make it clear what is original and what is new.

During our time in the archives, we discovered one thing that hasn’t changed much – archaeologists love site dogs.

Site animals
Some pictures of very good dig dogs over the years… and one very cute baby fox (bottom left)!

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.

Shades of the Past

By Julia Commander, Jessica Betz Abel, and Anna O’Neill

We’ve shared a few insights into the monumental limestone we’ve been treating at our Conservation Lab Annex (CLA). You may have noticed a consistent color scheme: tan. The surfaces of the doorways are intricately carved and decorated with faience inlay, although we mainly see a variety of neutral tones.

Doorway 1 in the lab

To get a sense of how these architectural elements would have looked when they were made in Memphis, Egypt around 1213–1203 BCE, it helps to understand the materials and their state of deterioration. Luckily, the Penn Museum Archives has extensive records from the 1920’s Memphis excavations, which provides some further clues about these objects.

Searching through archival materials, we found detailed notes about each object as it was excavated, as well as extensive watercolor illustrations. We can see brilliant colors in the drawings and notes referencing traces of paint and inlay material.

Archival illustrations of Merenptah columns
Archival illustrations of Merenptah columns

We even see that the doorways are illustrated with brilliant blue and teal colors.

Archival illustrations of Merenptah palace doorways
Archival illustrations of Merenptah palace doorways

Some of the illustrations appear to extrapolate data from small traces of material. Do these colorful illustrations line up with what we’re seeing now in the material itself?

To explore a little further, we brought the Crimescope out to CLA to investigate using multispectral imaging. This technique has been discussed on the blog before, and we were particularly interested in infrared (IR) imaging of the faience inlay. While there are different types of faience material, some types related to Egyptian blue pigment produce the same luminescent response induced by visible light.

Searching for IR luminescence pointed us to a tiny area of inlay in the upper corner lintel fragment. The tip of one stripe glowed brightly, which corresponds to a pale green color that’s visible in normal lighting.

Visible light (VIS)
Visible-induced infrared luminescence (VIL)
Detail with VIS/VIL overlay

This result suggests that we’re seeing a deteriorated state of formerly bright blue/green/teal faience. While we did not see every trace of the degraded inlay light up in infrared imaging, this small hint corroborates what we’re seeing in the archival illustrations.

We plan to continue using multispectral imaging to explore decorated surfaces when we’re back at CLA. Stay tuned!

Monumental but gentle

by Anna O’Neill, Julia Commander, and Jessica Betz Abel

Hello from the Penn Museum Conservation Lab Annex (CLA)! Since Lynn’s introduction, we’ve had a little bit of time to settle into our new, off-site facility and get started on some seriously big projects. Our primary task here is working on architectural elements that were part of the palace of the Pharaoh Merenptah, who ruled Egypt from Memphis from 1213–1203 BCE. We have doorways, windows, and other objects from the palace which will be displayed in the new Ancient Egypt & Nubia Galleries to give visitors the experience of being in an ancient Egyptian building. But first, we have to put them together!

The warehouse section of CLA, with pallets of fragments from the Merenptah palace complex.

We have four doorways that will go into the galleries, all of which are very large and in many pieces. They are made of limestone and intricately carved, with traces of inlay and paint. Our first project is Doorway 1, which will be about 12 feet tall once it’s all together. It’s never been displayed before, but it was partially treated in the past. Some fragments are joined together with adhesive and metal pins, and we can tell that some of the decorated surfaces were coated with a consolidant. The fragments are also very dark and dirty from almost 100 years in storage.

Doorway 1 is in thirteen major pieces, which were all on different pallets when they were moved to CLA. With a little bit of effort and a lot of maneuvering with pallet jacks, we grouped the fragments together. It was very satisfying to figure out how all the pieces fit together and form a door!

Doorway 1 coming together on pallets in the lab section of CLA.

Since we’re using Doorway 1 as our pilot project to figure out how we’ll treat the rest of the palace objects, we’ve spent a lot of time testing different conservation approaches. Since the doorway is discolored with dirt and one or more old coatings, we’ve been experimenting with gel cleaning and found two methods that work well for what we need – hot agar and Nanorestore gels® Peggy. We’ve talked about using other kinds of gel before.

Agar is a product of red seaweed and contains a polysaccharide called agarose. When it’s dissolved in water and heated, agarose forms long molecular chains – that means that when it sets, agar becomes a rigid gel that can be peeled up as a sheet without leaving problematic residues behind. The long agarose chains create pockets that hold solvents on the surface of the object, allowing them to work on grime or coatings without soaking in too deeply. You can add different cleaning solutions to agar, but plain deionized water gave us the results we wanted. We dissolved agar in deionized water and heated it in the microwave to form the solution, then poured it directly onto the surface of the stone and allowed it to cool. Applying it as a liquid means that the gel conforms well to the irregularities in the object and lets us get into all the nooks and crannies.

Action shots showing the application of agar to the surface of Doorway 1.

The Peggy 6 gel is made of poly (vinyl acetate) and comes as a thin polymer sheet. It feels a little like the gummy hands you can stick on windows – stretchy and flexible but strong. Like agar, the Peggy gel can be used with different cleaning solutions but we stuck with deionized water. The gel is laid on the surface of the stone to let the water do its work on the grime. Because the Peggy is a stretchy sheet, it can skim right over delicate carvings that might contain pigment. Another advantage of the Peggy gel is that it’s reusable – we just rinse it out in deionized water and use it again.

The Peggy 6 gel in action.

To clean Doorway 1 we used a combination of the agar and Peggy gels. Both gels soften the dirt and coating, and often looks pretty grimy when they’re peeled up. Once the gel is removed, the stone is wiped with cotton and more deionized water to remove even more dirt. We were pretty pleased with the difference between the cleaned and dirty surfaces, and using the gels meant that the process was much more efficient and gentler on the stone than using swabs.

Other parts of the treatment include reversing old repairs (or deciding when to leave them be), assembling fragments, and figuring out how to display the doorway in the gallery. We’ll check back in later with more monumental updates!

But this warehouse is Just Right

By Lynn Grant

Penn Museum’s Conservation Department is charged with reviewing, documenting, and stabilizing every artifact that goes on exhibition in the Museum. Most of the time, the objects tend to be in the ‘smaller than a breadbox’ (if you don’t recognize that category, check out this article) and are dealt with fairly expeditiously, especially once our labs were renovated in 2014. Before that, larger objects were a challenge, which was one factor in turning a gallery space into the Artifact Lab.  Even with the renovated lab, working on large objects (large textiles, eagle feather bonnets, carved elephant tusks) requires negotiating with colleagues – or sometimes just having a group session to free up the space as quickly as possible. 

Four conservators working on one carved elephant tusk to reduce the time it monopolized that working space.

But then there’s the ‘Wayyyyy bigger than a breadbox category”, aka monumental artifacts – too big to bring into lab. Sometimes we’ve dealt with this by bringing the lab to the artifact (Tang Taizong, Buddhist murals, Kaipure, the Sphinx).

Conservator Julie Lawson cleaning the Tang Taizong horse reliefs in the gallery.

For the renovation of our Ancient Egyptian and Nubian galleries, though, the sheer number of monumental artifacts, including parts of a Pharaonic palace was (nearly) overwhelming.

Fortunately, planning began early. When we assessed all the various pieces, we came out with three categories: 1) can fit into lab; 2) too large for lab but not too large to leave building; and 3) too large for lab and too large to leave building. This last category included pieces that were too large and/or heavy for our current freight elevator and loading dock. We ended up closing the Museum’s Lower Egyptian Gallery in the summer of 2018 to permit the objects in Category 3 to be treated in situ.

NYU Conservation Center graduate student Adrienne Gendron working on a column drum from the Palace Complex of Merenptah in our Lower Egyptian gallery.

This was not an ideal situation, not only because it deprived visitors of access to those objects longer than we hoped; but also because the space is not very suitable and would be adjacent to or part of a construction site for the next 5 years. However, you can’t argue with physics. Well, you can, you just won’t win.

For artifacts in Category 2, we needed to find a space where we could store them and do the necessary conservation and reconstruction for the new installation. This was not an easy search and the University’s Facilities and Real Estate Services (FRES) were instrumental in helping us with the hunt. We needed a facility that was large enough to store the objects; had ceilings high enough to accommodate the re-erection of the large architectural elements; was secure or could be made so; could be adapted as a conservation work space; and was within an easy commute from the Museum. The hunt was long and hard: either the ceiling wasn’t high enough or the distance from the Museum too far or the neighborhood was too iffy, or there weren’t big enough loading docks to load/unload our monumental babies.

We finally located a space we agreed could be made to work – about 50 minutes from the Museum but it was big enough, had the ceiling height, had three loading docks – one of which was big enough to bring the truck inside (you really don’t want to be unloading Egyptian limestone in the rain), and it had areas that could be adapted as lab/office spaces.

Home sweet warehouse.
This shot shows our storage area as we first saw it (left) and as it was when we took possession (right).

We started moving artifacts out to the Conservation Lab Annex (CLA) last year and began serious conservation work in September.  I’ll let our CLA team introduce you to their space and their work in upcoming blog posts.