Ugly Object of the Month — August 2018

by Caroline Roberts, Conservator

This month’s Ugly Object takes the cake for being both incredibly interesting and really, really ugly. What exactly is this rather scraggly looking textile fragment? We’re not entirely sure, although its report suggests that it might have once been part of a cap.

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Scrap of wool sprang textile, possibly from a cap. 18.5 x 8.5 cm. Roman period. Karanis, Egypt. KM 12797.

This bit of cap — discovered at Karanis, Egypt — was made using a technique called sprang or nålebinding, an ancient precursor to knitting in which loops of yarn are interlinked using a single needle. Are you a yarn enthusiast or experimental archaeologist and want to try the technique for yourself? Check out Suzanne’s 2016 blog post about an ugly sprang sock, which features links to pages detailing how to knit/link your own ancient sock.

There are other cool things about this sprang fragment, one being its color. We suspect it could be an organic red dye, although analysis would be needed to confirm this. Rose madder, a red colorant derived from the processed roots of the madder plant, was used frequently as a pigment in Roman Egypt and might have been used to color our cap frag. Another cool thing is the black overcast stitches that run along one edge. These could very well be part of the cap’s original construction, or perhaps an ancient repair.

This and other less frequently seen Karanis textiles will be on display in the upcoming Kelsey exhibition Ancient Color, opening February 8, which explores the sources, uses, and scientific investigation of color in the Roman world.

Investigating color on a Roman-Egyptian mummy portrait

by Caroline Roberts, Conservator

This week a team from the Detroit Institute of Arts conservation department traveled to the Kelsey to take a closer look at one of our Fayum mummy portraits. The portrait is normally on display in the Dynastic Egypt gallery and is dated to the Roman period of Egypt (79–110 AD). The woman featured in the portrait is clearly of means, as her gold earrings and necklace, colorful gems, and purple robe indicate. We were curious to learn more about the colorants that were used to paint her portrait and to look for painting details that have become harder to see over time.

Christina Bisulca, conservation scientist at the DIA, brought along a portable spectrometer to identify pigments on the painting. She found evidence of pigment mixtures in multiple areas of the portrait, including the flesh tones, the oval gem at the center of the woman’s pendant, and the drapery of the robe. It appears that the various shades of purple in the robe were likely created by mixing and laying blue and red pigments and dyes, for example. Further analysis is needed to verify these results.

Aaron Steele, the DIA conservation department’s imaging specialist, brought along their powerful infrared camera to see if underdrawing might have been used to sketch the sitter before paint was applied. Although underdrawing was not immediately visible, details of curls along the hairline and sectioning of the woman’s hair could be seen in the infrared images. Details of paint application next to the woman’s face are also much more visible in the infrared. I also had the chance to capture ultraviolet images and produce infrared false color images which provide good information on the distribution of certain pigments (including rose madder and Egyptian blue) over the surface.

We look forward to learning more about the Fayum portrait over the next year and to featuring the results in an upcoming Kelsey exhibition about color in the Roman world. Many thanks to our friends at the Detroit Institute of Arts for their support of this project!

Ugly Object of the Month — April 2017

CAROLINE ROBERTS, Conservator, Kelsey Museum of Archaeology

April’s Ugly Object isn’t an object per se. It’s a specimen — a shell — and it was excavated at Karanis during the 1924–25 field season. It’s rather small and unprepossessing. But to me this shell is a thing of beauty. Why? It is a murex shell, and was once the likely carrier of shellfish purple (or Tyrian purple), one of the most valuable dyes in antiquity. Pliny wrote at length of the Roman passion for purple, and described in detail the extraction and processing of the color from a gland found in the throat of the snail. The dye produced a range of purples from magenta to purple-black. One can imagine the vast numbers of snails that would have been needed for a dye vat large enough to color the yards and yards of textile used in the elite fashion industry of Rome. Pliny cites an observation by the 1st-century BC biographer Cornelius Nepos that a pound of dye would have sold for 100 denarii — about half of the annual salary of a professional soldier. This was some seriously valuable stuff.

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Murex snail shell KMA 3712, Graeco-Roman Egyptian galleries, Kelsey Museum

Tyrian purple, like many other natural colorants, has now been chemically synthesized. We can buy a shirt or sweater in purple or any other color today at very little expense, which makes it hard to relate to the craze that drove people to seek out the murex snail on Mediterranean beaches. I can’t think of a color today that screams “bling” the way purple did in the ancient Roman world. Can you?

You can spot the murex shell in the Graeco-Roman Egyptian galleries on the first floor of the Kelsey’s Upjohn wing.

References to the text of Pliny the Elder, The Natural History (Historia Naturalis) Book IX, Chapter 63 are from a translation by John Bostock, M.D.  London: George Bell and Sons, Covent Garden. 1890.

Ugly Object of the Month — October 2016

BY CAROLINE ROBERTS, Conservator

It’s October, folks, and that means the season of decorative gourds and dressing up in festive costumes is upon us. This is partly why I chose this ceramic figurine of Harpocrates as October’s Ugly Object.

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Ceramic Harpocrates figurine, with intact ground and paint layers. 2nd–3rd century AD. KM 6449.

Who, you might ask, is Harpocrates? He was a deity worshipped in Ptolemaic Egypt, a child version of the sun god Horus. This ceramic figurine bears many of Harpocrates’ signature traits, such as a finger raised to his mouth, the double crown and crescent moon, and a garland. This figurine is also probably one of many identical ceramics produced for mass consumption.  But what’s really cool, to me, is what’s going on the surface: this Harpocrates is seriously decked out in a variety of well-preserved paint colors, which include black, pink, red, yellow, and blue. Equally cool is the likelihood that other ceramics like this one, many of which retain no polychromy at all, were just as colorful.

While documenting the figurine I thought it might be worth doing some technical imaging of the pigments, to get a preliminary idea of what they could be. The longwave ultraviolet luminescence (UVL) image revealed that the pink garland is likely made of rose madder pigment, and the visible-induced infrared luminescence (VIL) image showed traces of Egyptian blue pigment on the structure next to Harpocrates, as well as on his crown. The remaining colors are likely iron-based earth pigments, and the black carbon-based. Other techniques that could help us confirm these results include XRF or FTIR spectroscopies, the first of which (like imaging) is non-invasive.

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Left: UVL image showing orange autofluorescence of madder in the garland. Right: VIL image showing luminescent Egyptian blue stripes to the right of the figure, as well as in the crown.

This highly colorful Harpocrates will be on display at the Kelsey starting February 10, 2017, as part of the upcoming special exhibition The Art of Science and Healing: From Antiquity to the Renaissance, curated by Pablo Alvarez.

Analyzing Roman wall paintings

BY CAROLINE ROBERTS, Conservator, Kelsey Museum of Archaeology

When I think about color in antiquity, I like to imagine how colors have weathered, or changed chemically over time, and the ways these changes impact how we see ancient paint surfaces. Ancient paint can be found on terracotta figurines, marble sculpture, and — most visibly — on wall paintings. The Kelsey Museum preserves a number of Roman wall painting fragments, and curator and professor Elaine Gazda has incorporated these artifacts into her history of art classes. One of Professor Gazda’s students, U-M senior D’Arcy Cook, has taken on the challenge of identifying the pigments from a group of these wall painting fragments.

D’Arcy is a chemical engineering major who is interested in archaeological chemistry and conservation science. Her primary research question was whether pigments on the Kelsey wall painting fragments matched what she had learned to expect based on published literature. To answer this question, D’Arcy used analytical techniques available in the Kelsey Conservation Laboratory and across campus. I felt this would be a great opportunity to learn more about artifacts in the Kelsey collection and to provide D’Arcy with experience analyzing ancient materials.

Using a scalpel, I removed milligram-sized samples of paint from the fragments. D’Arcy analyzed the samples using Fourier Transform Infrared Spectroscopy (FTIR), an analytical technique that identifies materials by detecting signals produced by their molecular bonds. Among other results, her analysis confirmed that Egyptian blue is present on one of the fragments — a pigment I also detected with a modified camera, and which we both observed using a polarized light microscope. Egyptian blue pigment was commonly used by the Romans on wall paintings and sculpture.

This project illustrates how technical research works best by incorporating multiple, cross-checking analytical techniques, and depends on scientists, art historians, and conservators to happen. Many thanks D’Arcy, to Elaine and the Kelsey curators, and to the U-M Chemistry department and EMAL laboratory for their help with this research!

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Sampling photograph showing plaster and paint layers on a piece of wall plaster.

 

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Visible (VIS), infrared reflected (IRR), infrared reflected false color (IRR-FC), and visible-induced infrared luminescence (VIL) images. The white luminescence in the VIL image shows the presence of Egyptian blue.