Things are getting heated!
The science of colors in a colorful new Learning Lab
By Adam Sarouji
Based on research by former Andrew W. Mellon Assistant Conservator Kathryn Etre
Take a look at the colors on this Praying Mantis Plate from the Art of the Americas Gallery.
We can see red, black, white, and an interesting purple color...
What if we told you it isn't purple at all...
It's actually a shade of red!
Let's get rid of the other colors and take a closer look...
See it now?
How about now?
This deceptively purple color is called Panama Purple, and is found on ceramics in the Coclé region of Panama between 500 and 1100 CE.
But what exactly is Panama Purple?
Panama Purple is Hematite!
Also called red ochre, hematite is an iron-based pigment commonly found on ceramics throughout the world. Its rust-color comes from just that: iron oxide. When ground into a fine powder and mixed with slip (a mixture of clay and water), it creates a vibrant red pigment such as the one used on the praying mantis plate shown here.
Former Andrew W. Mellon Assistant Conservator Kathryn Etre used X-Ray Fluorescence (XRF) to find out what elements or minerals are present in Panama Purple. She learned that not only does this purple pigment contain a lot of iron oxide, it is nearly identical to the red ochre used on the same plate!
If Panama Purple and red ochre are so similar, why is the color so different?
Etre's research discovered that when hematite is heated up in various environments, its color becomes more grey. If the temperature and heating time are tuned just right, a deceptively purple color can be made.
The Recipe for Panama Purple
Etre identified two possible methods for accomplishing Panama Purple:
The first method is by heating hematite at temperatures as high as 900°C for multiple hours. Researchers are not sure what kind of kilns ancient Panamanians may have used, but we do know that they had access to braziers (a special type of stove often used to melt metals such as gold and silver) that could reach temperatures over 1000 °C.
The second method is by heating hematite at lower temperatures in a very low oxygen environment. This process is called reduction firing. A reduced environment can be created by burying the hematite and hot coals, or by closing all the openings, or dampers, on a kiln, sealing the hematite inside.
Ancient Artisans and Ceramic Scientists!
When we think about colors in antiquity, we often imagine naturally occurring dyes and pigments from drying plants, squeezing fruits, grinding rocks and minerals, or extracting parts from animals. But makers across time and space have often gotten creative with the manufacturing process itself. Panama Purple is just one of many examples of makers utilizing a deep understanding of material science and high degree of precision in their firing techniques in creating these fantastic displays.
Explore the science behind Panama Purple and see the Carlos Museum's new colors in the Learning Lab today!
Feeling bookish? Scan the QR code below to read Kathryn Etre's original research!
More of a visual learner? Scan the QR code below to watch Kathryn Etre's presentation!
Find more Panama Purple in the Art of the Americas Gallery!
Pedestal Plate with Praying Mantis Motif, 800-1000 CE
Pedestal Plate with Praying Mantis Motif, 800-1000 CE
Fragmented Pedestal Plate with Dancing Crocodilian, 800-1000 CE
Fragmented Pedestal Plate with Dancing Crocodilian, 800-1000 CE
Vessel with Inverted Jaguar Motifs. 800-1000 CE
Vessel with Inverted Jaguar Motifs. 800-1000 CE
Pedestal Plate with Anthropomorphic Crocodile
Pedestal Plate with Anthropomorphic Crocodile
Behind the Research: Kathryn Etre
Former Andrew W. Mellon Assistant Conservator for the Michael C. Carlos Museum.
Kathryn became the Carlos Museum’s first Mellon Fellow after completing a fellowship at the Detroit Institute of Art. She undertook research to source obsidian objects and to identify the purple colorant on slip-decorated ceramics from ancient Panama. She contributed to collaborative courses taught in Physics and Environmental Sciences. As Mellon Assistant Conservator (2012-2015) she managed treatment for the reinstallation of the Greek and Roman Art galleries and also worked as conservator at Malqata, Egypt and at Oǧlanqala, Azerbaijan. She has an undergraduate degree from Boston University with majors in History, Archaeology, and Classic Civilizations and graduated from the Institute of Archaeology of University College London with a Masters of Science in Conservation for Archaeology and Museums. Kathryn is a Professional Associate of the American Institute for the Conservation, and she is now the Director of Conservation at the Mississippi Department of Archives and History (MDAH) Museum Division.
Conservators can do it all!
Museums house a wide variety of objects: books, photographs, paintings, ceramics, rocks, minerals, and list goes on. Museum conservators are trained to be able to preserve, maintain, and restore pretty much any object you can think of! Some conservators specialize in recreating missing sections of paintings brushstroke by brushstroke, and others like professional dry cleaners, caring for the oldest of garments. There is no one way to define a conservator and their skills vary from museum to museum. One moment a conservator could be using highly-specialized lab equipment and spend the next scrubbing stains with soap and water.
Bibliography
Etre, K. (2016). Four-Color Polychrome Pottery from the Coclé Region of Panama: Investigating the Production of the Purple Colorant. Michael C. Carlos Museum of Emory University.
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