objects conservation

Ugly Object of the Month — September

By Caroline Roberts, Conservator

Hey, Ugly Object fans! It is great to be back at the Kelsey part-time and working with the collection again. One thing I’ve missed most about being away from the museum are the surprises — the chance discoveries than can happen while examining artifacts up close. This month’s Ugly Object is a rather unassuming funerary stela from Terenouthis, Egypt, showing a woman with upraised arms. At first glance, it doesn’t look like there’s much going on here beyond the carved figure, and I was not expecting to find more than a few small traces of pigment in the woman’s chiton. But as soon as I shined a UV light over the surface, hidden figures emerged! Look closely and you might be able to see a fringed shroud hanging over the woman’s left arm, an Anubis figure reclining on a plinth to her left, and below the woman’s feet … a painted inscription! 

Limestone funerary stela KM 21021 from Terenouthis, Egypt, late 2nd–early 4th century CE. Left, under visible light; right, under longwave ultraviolet light.

At what point did these images disappear? A photograph of the stela shows faint traces of the shroud, canine figure, and inscription, but the fact that they aren’t mentioned in the Terenouthis stelae’s published catalogue suggests that these elements had nearly disappeared by the early 1960s. Today, they are all but invisible to the human eye. Thankfully, some trace of the original paint remains in a form that is sensitive to UV light. This makes me wonder … how many other stelae have images and inscriptions that await rediscovery?

Stay tuned for more!

August News from the Conservation Lab — Conservators in the house!

By Caroline Roberts & Suzanne Davis

We are back in the lab!!!

Suzanne and I are very excited to be back at the Kelsey doing conservation and collection-focused research a few days a week. Here we are preparing some of the Kelsey’s Terenouthis stelae for photography.

selfie of two women wearing masks
Socially distanced selfie with stelae from Terenouthis, Egypt, 3rd–4th centuries CE.
Seated figurine carved from alabaster

Ugly Object of the Month — April 2020

By Caroline Roberts, Conservator

Greetings, Kelsey blog fans! I hope that you are all safe, healthy, and keeping it real at a sound social distance. We weren’t about to let today’s uncertainty get in the way of our ongoing celebration of Ugly Objects. So, it brings me great pleasure to present April’s pick: a seated female figurine from Seleucia. Seleucia on the Tigris was a Hellenistic capital city located south of present-day Baghdad and excavated by the University of Michigan from 1927 through 1937. Over 3,500 objects were recovered from Seleucia, including a myriad of figurines made of bone, ceramic, and stone.

Seated figurine carved from alabaster
Seated female figurine carved from alabaster, with bitumen repair resin at the neck and on the base. H. 12.8 cm. Seleucia on the Tigris, Iraq, 150 BCE–200 CE. KM 15879.

Our seated figurine is made of alabaster, a soft sedimentary stone with a uniquely translucent quality that made it a suitable material for window panes. Alabaster is easy to work, so we find a lot of vessels and figurines carved from it. But that same quality causes the stone to deteriorate easily. The alabaster block used to create this seated figure has broken along its bedding planes, causing the right arm to shear clean off the front of the statue. This type of inherent flaw might be what caused the head to detach — probably while the figurine was in use. Look closely and you can see traces of bitumen resin along the neck and on the base, signs of someone’s effort to repair the figurine in antiquity.

It amazes me how much we can learn from artifacts that were excavated nearly a century ago! Please keep reading our blog and visit the Kelsey website for opportunities to learn more about our collection.

multispectral imaging of an ancient stone stela.

News from the Conservation Lab — Work in Progress

By Caroline Roberts, Conservator

 Conservators wield some impressive photo-processing skills, in no small part because of the extensive photographic documentation we do in our work. We use our image-processing skills for research purposes, too.

Right now I’m taking multispectral photos of limestone funerary stelae from the Roman Egyptian city of Terenouthis so that I can begin to characterize the pigments that were used to paint them. Pigments reflect, absorb, and/or luminesce ultraviolet, visible, and infrared light in characteristic ways, but capturing a good image of these photo-chemical responses can be challenging.

Luckily we have access to the British Museum’s Technical Imaging web resource, a free downloadable toolkit that includes image setup, capture, and post-processing guidelines. The BM’s protocol has become an essential part of our own multispectral imaging setup, and an important research tool in my survey of color on the Kelsey’s stone collection.

multispectral imaging of an ancient stone stela.
Left: Limestone funerary stela KM 21107 from Terenouthis, Egypt, late 2nd–early 4th century CE, during multispectral image capture. Right: Infrared / visible image alignment in the British Museum technical imaging workspace.
small marble hand and arm

News from the Conservation Lab — Pretty in Pink

By Caroline Roberts, Conservator

I’ve been spending a lot of quality time in collections storage lately and have noticed something curious: an abundance of pink! Namely, ancient pink pigment. Why is this so interesting? Because the pink most frequently used in the ancient Mediterranean was made of madder root, a plant-based dye that was used to color textiles as well as a pigment on objects.

Like other organic pigments, rose madder is highly light sensitive and prone to fading. The occurrence of rose madder on so many artifacts in the collection surprises me, given what we know about its fugitive nature. Rose madder also has a unique chemical property that causes it to luminesce, or glow, an orange-pink color when exposed to ultraviolet light. A quick look with a UV LED flashlight can help confirm whether or not the pink on an object is madder.

small terracotta hand and arm

Marble sculpture fragment KM 1931.441 from Seleucia with pink pigment between fingers and inside elbow.

sculpture fragment under two different kinds of light
Visible and ultraviolet-induced luminescence (UVL) images of KM 1931.441 showing orange-pink luminescence of rose madder.

Despite its tendency to fade, I am finding pink on everything from terracotta figurines to marble sculpture to limestone grave markers. I’m also finding it in different hues and on different decorative elements, from flesh tones to jewelry to architecture.  It turns out pink is everywhere at the Kelsey, and it is pretty fascinating.

small headless terracotta statuette with pink painted necklace
Marble sculpture fragment KM 1931.15 from Seleucia with pink-colored necklace.
stone with pink pigment
Remnants of pink paint on the surface of KM 21107, a limestone funerary stela from Terenouthis.
carved funerary stela

November News from the Conservation Lab — Stone Survey Discoveries!

By Caroline Roberts, Conservator

 The stone condition survey is well underway, and I am just floored by the richness and variety of the Kelsey’s stone collection. We’ve got limestone that is packed full of shell fossils (fig. 1), alabaster that has weathered in a way that it looks like a sea sponge … and, best of all, so much of the material comes from sites that were excavated by the University of Michigan. If I had to choose the most exciting artifacts I’ve encountered so far, it would be those from Karanis, Seleucia, and Terenouthis. I’m a self-professed ancient color geek, and an incredible number of these objects still have pigment preserved.

limestone with fossils
Figure 1. Shell fossils visible along the side of KM 29001, a limestone funerary stela from Terenouthis, Egypt, late 2nd–early 4th century CE.

Take the Karanis stone. I’ve seen hefty jar bases that have traces of pigment and ground still in place, and a libation altar decorated with a vivid orange-red pigment (red lead?) barely visible under a thick layer of burial dirt. At least half of the Seleucia sculptures I’ve examined have traces of pink pigment, including one with a highly detailed painted necklace. I’ve spent years studying the Terenouthis funerary stelae, and even these continue to surprise me. I spotted blue-green pigment on a well-preserved stela that I am eager to investigate further (fig. 2).

carved funerary stela
Figure 2. Limestone funerary stela from Terenouthis, Egypt, late 2nd–early 4th century CE. Traces of green pigment can be seen in the figure’s left hand and on the recliner cushion. KM 21159.

In addition to revealing the extent of surface decoration on the Kelsey’s collection of stone, the survey is also helping me determine which artifacts are in need of treatment or rehousing. It’s amazing to me how much there is to learn from objects in the collection even now, in some cases nearly ninety years after their discovery.

pile of books

News from the Conservation Lab — On Research and Writing

By Caroline Roberts, Conservator

One of the best parts of being a conservator, in my view, is the opportunity to do research. Here at the Kelsey, we do a lot of research in support of the conservation and care of the Museum’s collections as well as Kelsey-sponsored archaeological field projects. In our efforts, we accumulate a lot of books. Sure, plenty of information we use comes to us in PDF or other non-print format. Yet somehow, even in this digital age, books of all shapes, sizes, and subjects have taken up residence in our lab at a starling rate, to the point where things start to go missing among the piles. From time to time — often at the behest of a lending library or a fellow researcher — we let go of a few of them. A recent “return” pile made me laugh. The stack contained books on trade routes, conservation materials, geochemistry, Egyptian painting, and at least three other seemingly unrelated topics. The only thing these books had in common was the fact that they are bound blocks of text with chapters, references, and page numbers. They were otherwise complete strangers, hailing from disparate corners of the bibliographic universe.

pile of books
A conservator’s book pile.

Why so many books? One reason is that Suzanne and I have made a big push recently to publish some of the research we’re doing. This means checking sources, conducting literature reviews, and verifying information left and right. The research itself has been pretty wide-ranging, from computational imaging of ancient graffiti to chemical analysis of pigments on artifacts. This is where the diverse subject matter of the books in our lab starts to make sense. Conservators often find themselves needing to answer many different types of research questions. Sometimes these focus on figuring out how cultural materials were made and used. But more often than that, they’re about developing ways to characterize and slow artifact deterioration. Cultural heritage preservation is our primary goal, after all! Conservators have always been active in presenting their work at conferences, and an increasing number are publishing their practical experiences in books and journals. This means more peer review, and even more helpful references to fill our lab with. All good things, in my book!

Artifact investigation

CAROLINE ROBERTS, Conservator

I love a good mystery, and nothing (save a really good crime novel) is better than an artifact mystery. I love the thrill of investigating an object, identifying its agents of deterioration, and nabbing those culprits one by one. I also really enjoy teaching new conservators how to use investigative tools to make their own observations. I recently spent a day looking at an object with Ellen Seidell, a U of M junior who is interning in our lab. The ceramic bowl — excavated at Karanis in 1929 — was covered with feathery white crystals, as well as a drippy, peeling surface coating. I had my suspicions as to what these were, but wanted Ellen to learn for herself how to identify unknown materials.

Image_01 march

Left: Ceramic bowl before treatment. Right: bowl under longwave ultraviolet light.

To do this, we examined the bowl under longwave ultraviolet light. This is a useful tool not only for crime-scene investigation, but also for identifying varnishes and coatings. Ellen and I could immediately see a bright yellow luminescence on the surface. We then performed a chemical test to determine that the coating was cellulose nitrate — a material used to treat newly excavated artifacts in the 1920s and ’30s. Finally, we determined that the white crystals were salts. Water-soluble salts like these can be absorbed into artifacts during burial. Fluctuations in humidity can cause salts to crystallize and re-crystallize inside the object, which can cause damage to artifact surfaces.

So what did we do with this evidence? First, we decided to remove the salts. I felt that this would be a good experience for Ellen, since not all salty bowls have the advantage of being in a climate-controlled museum, and since monitored desalination is an important conservation skill. Next we addressed the coating, whose identity allowed us to choose an appropriate solvent for its removal — which Ellen did herself. The treatment is complete, bringing the case of the salty, peeling bowl to a close (for now).

Documenting Demons in the Infrared

BY CAROLINE ROBERTS, Conservator, Kelsey Museum of Archaeology

This demon bowl, which was excavated by the University of Michigan in the 1930s, now resides in the Kelsey Museum. It comes from the ancient city of Seleucia, which is located not far from Baghdad along the Tigris River. If you look closely at the bowl, you can see that the inside is covered in rows of what looks like text, as well as four line-drawn figures. These are demons (hence the title “demon bowl”) and they reveal the function of the bowl: to trap demons.

Image_01
Two views of the “demon bowl” (TMA 1931.455). On the left, a visible-light image; on the right, an infrared reflected image. Photos by Aaron Steele.

Unfortunately, the bowl has a dark gypsum crust which obscures these super cool and creepy demons. Fortunately, we know there are ways to see though the crust, and Madeleine Neiman, who worked as a Samuel H. Kress Conservation Fellow in the Kelsey conservation lab during the 2014–15 academic year, spearheaded a project to investigate the bowl. This included looking at the bowl with infrared reflected (IRR) imaging.

IRR is a technique used by conservators to reveal difficult-to-read painted inscriptions, or drawings under paint layers. The Detroit Institute of Arts Conservation Department has its very own Goodrich SWIR infrared camera. The SWIR’s capture range surpasses that of the modified DSLR camera we use for IRR at the Kelsey, and Madeleine found that infrared light at this higher range could pass through the bowl’s darkened crust. So we packed up the bowl and drove to Detroit to see what we could see.

The Goodrich camera was able to reveal the bowl’s inscription, thanks to the IR transparency of the gypsum crust and the heavy IR absorption of the inscription. The result is a higher visual contrast between the inscription and the surrounding ceramic, making it easier to read. Okay, actually “reading” it is hard to do, given that the inscription is not real script! But you get the picture. What I found fascinating is the high level of detail revealed in the images of demons on the bowl, including flames, raised arms, and scary faces. These unique characteristics are all the more visible thanks to the power of infrared light.

Image_02
Detail of a demon in the infrared reflected image. Photo by Aaron Steele.

I’d like to thank our DIA colleagues Aaron Steele and Aaron Burgess for taking the time to capture these images, as well as Madeleine Neiman for helping us uncover the demons who have been hiding underneath that dark (and scary) crust!