This article was originally published on the defunct Ancient World Magazine website and is now re-published here.
If you’ve ever been to an archaeological museum with a collection of Greek pottery, you’re no doubt familiar with rows of black- and orange-coloured vases neatly arranged in display cases. Vast amounts of these pots, both entire vessels as well as countless fragments, have been retrieved from excavations, in addition to specimens obtained from (potentially illegal) auctions and antiques markets.
Especially ubiquitous are red- and black-figure vases. These were intended, like all finely decorated pottery, as quality tableware. Extremely wealthy ancient Greeks and Romans also used silver tableware, of which almost nothing survives. For cooking and other purposes, simpler and cruder vessels were used that were generally not decorated in any fashion. These kitchen vessels were usually fired at much lower temperature and made from coarser clay. Fine pottery was usually shaped using a potter’s wheel, coarser vessels were often just shaped by hand.
You can actually hear the difference between fine tableware, fired at higher temperatures and made from fine clay, if you drop a sherd on a hard surface: a fragment of the more expensive type of pot will ring out, whereas a fragment of a vessel used for cooking or storage and made from coarser clay will sound dull in comparison. (Note: don’t start throwing pottery around without express permission!)
Red- and black-figure pottery
Black-figure technique is the oldest of the two styles of painting. It was invented in Corinth around 700 BC, though Corinthian vase-painting of this early period is usually not referred to as “black figure”. By the later seventh century BC, Athenian vase-painters adopted the technique, applying it to larger types of vessels that were soon to become more popular than the generally smaller Corinthian pots. Athenian black-figure eventually became dominant, displacing Corinthian pottery by the early sixth century BC.
Before painting, the surface of the pot was burnished and polished before it completely hardened out. The painter sketched the outlines of the scenes he (or, indeed, she) wanted to paint. These were then coloured in using a fine clay slip with a different consistency and makeup from the clay used for the pot itself. The painted slip was then allowed to dry.
After the slip had dried, the artist added details, such as folds in clothing and eyes, through incision using a tool with a sharp point, which revealed the colour of the pot underneath. Other colours could then be painted over the darker slip, such as red, yellow, or white. White was made from fine white clay. The white clay could be mised with yellow ochre to create a yellow colour. Red was made of red iron oxide.
The red-figure vase-painting technique was first developed in Athens (or somewhere in the region controlled by Athens, i.e. Attica) in ca. 530 BC. Red-figure is essentially the reverse of black figure: the background is filled in with a fine slip and has a black colour after firing, while the figures are reserved. Details are added using fine brushes instead of through incision, allowing the artists to add a greater level of detail to their art.
Red-figure existed side by side with black-figure for a while, with some artists even making so-called “bilingual” vases, in which one side was executed in red-figure and the other in black-figure. The two contrasting scenes on individual bilingual vases are often similar. Red-figure would remain in use until well into the third century BC.
The firing process
In ancient Greece, pottery was made in pottery workshops that usually employed a number of people. Some of them would harvest and clean the clay, while potters shaped the vessels and painters decorated them. They were probably family businesses. Sometimes, potter and painter were the same. There are a few vases that depict such workshops. After the painter was done with the vase, it would be left to dry in the open air. A few painters and potters actually signed the vessels that they helped create.
Vessels that were ready to be fired were stacked inside a kiln where temperatures would reach at least 450 degrees Celsius. The conditions inside the kiln were carefully monitored, perhaps by leaving smaller pieces of pottery in a place that was easy to observe or reach through a spy hole. The bright colours and deep blacks of Attic red- and black-figure vases were achieved through a process in which the atmosphere inside the kiln went through a cycle of oxidizing, reducing, and reoxidizing.
During the oxidizing phase, the ferric oxide inside the Attic clay achieves a bright red-to-orange colour. By contrast, clay from e.g. Corinth is paler in colour. During this stage, the temperature inside the kiln reaches perhaps 800 degrees and air is allowed into the kiln through a vent (hence, “oxidizing”, as the air adds oxygen to the atmosphere).
During the reducing phase, the air vent is closed and the temperature is increased to about 950 degrees. Moisture was added in the form of green wood or other damp materials to produce carbon monoxide instead of carbon dioxide. Combined with the ferrix oxide from the clay, the vessel would turn dark grey to black. The finer particles of clay used for the black gloss (i.e. the “paint”) would become sintered or fused as a result, changing permanently, unlike the coarser particles of the vessel itself.
In the final, reoxidizing phase of the firing process, some air was allowed back into the kiln and the temperature was slowly lowered to about 900 degrees. The oxygen turned the more porous reserved clay from gray to a bright orange-reddish colour. Since the earlier reducing phase had sintered the surface of the black gloss, preventing any further chemical reactions and leaving it the desired black colour.