I’m not going to hide that I’m an avid New York Times reader (don’t worry, I consume other media as well). I like it mostly for the crossword puzzles but also for the arts, style and food pieces. This past weekend, the Times featured an intriguing article about a kylix cup (https://www.nytimes.com/2023/04/19/arts/kylix-cup-greek-metropolitan-museum.html).
Now, I am definitely not well-versed in Ancient Greek pottery (shocking, I know). So let’s learn together. The kylix was the most common type of wine-drinking cup and thus a very common and popular pottery piece from Mycenaean times through the classical Athenian period. Usually there was decoration around the outside depicting mythology or everyday life and decoration on the bottom of the inside showing a dancing or drinking scene (https://www.britannica.com/art/kylix).
The NYT piece told the sordid story of a kylix that came to the Metropolitan Museum of Art (the Met) in New York in bits and pieces over the years and was reconstructed by the team at the museum. It is alleged that this may have happened by the cup being deliberately broken to get more money by selling the pieces. While I don’t think there’s clear evidence of that, what caught my eye about the article was the pottery itself.
We recently did an episode on ceramics (https://www.erevnamedia.com/podcast/episode/1c8f74a3/32-art-ceramics-and-electric-cars) so I was very curious about how these vessels were constructed. The particular piece that the Met reconstructed was attributed to the potter Heiron and the painter Makron. Hieron was an Athenian potter who has around 30 cups that bear his name as the artist and more that are attributed to him because of the style. The vast majority of those cups are thought to be decorated by Makron. Makron was a vase painter in Athens from 490-480 BCE. Only one signed example of his work has been found and others are attributed to him (like Hieron). Unlike vase painters at the time, Makron seems to have worked exclusively with Hieron and both of these artists are great examples of the red figure period of Greek ceramics.
Red figure vase painting developed in Athens around 520 BCE and was eventually replaced by black figure painting. It consists of red figures on a black background and was exported widely out of Athens and Southern Italy. (https://en.wikipedia.org/wiki/Red-figure_pottery)
Since we just learned so much about the science that turns clay into ceramics, I was curious about the science behind the art of making these kylix cups. So, say you were an ancient potter, like our friend Hieron, and you’ve just fashioned a kylix cup out of clay and dried it to remove some of the water molecules in the clay. What is the next step to make these beautiful and sought after cups?
The first phase after molding the clay into the shape is to apply a slip. Slips are clay slurries made of clay and water and they can act as a glaze and a glue to hold handles on cups (for example). The slips used by painters and potters in Ancient Greece contained a lot of iron. Iron is an interesting element that adds color depending on its oxidation state. Likely, the background would be painted with a iron-containing slip, while the figures would be not be painted.
For listeners of the podcast – you’ll remember oxidation from our episodes on pigments. Quickly, the oxidation state of a molecule is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. Think of it as “bonding potential”
Oxidation = loss of electrons during a reaction
Reduction = gain of electrons during a reaction
During this first hot, oxygen-rich firing, the iron dense slip would turn red (FeO3). But that wasn’t the goal for the whole piece. For red figure painting, the background was black, not red. So the potter would then add green wood to the fire. Green wood burns incompletely and releases CO2. This reduces the amount of oxygen present. This is a ‘reducing’ environment that leads the iron to change from FeO3 to FeO4. In the slip, the FeO4 would turn black and since the slip acts as a glaze, it would partially vitrify or sinter. Sintering is like vitrification in that it uses heat or pressure to form a solid mass but does not involving melting.
Check out our ceramics episode for more information about vitrification (link above)
After two different phases of firing, we know have a cup that is all black. What about the red figures? To get the red figures back, a third phase of firing is required. We now aerate the kiln to add more oxygen in, which creates an oxidizing environment. Areas that were not covered in the slip re-oxidize to FeO3, which produces a vibrant red color. We can now open the kiln to allow our cup to cool slowly and then take a sip of our favorite wine from it.
This type of firing is known as three-phase firing and was perfected in Corinth and Athens and then spread around the Mediterranean. (https://en.wikipedia.org/wiki/Three-phase_firing) It takes advantage of both the chromatic qualities of iron and the use of oxygen to achieve different reactions to produce the colors and to seal the cup so that you could drink wine from it.
I hope you find that as fascinating as I did. While we may never know if someone deliberately shattered the Met’s kylix and then sold them the pieces over 16 years, we do have a good idea about how it was created and the science that makes it so beautiful.
Photo: The Art Institute of Chicago