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!