ancient color – Page 3 – The Kelsey Blog

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.

image_01-oct — 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.

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

Leave a Comment / Conservation / April 19, 2016

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!

Image_01 a — Sampling photograph showing plaster and paint layers on a piece of wall plaster.

Image_02 a — 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.

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