Introduction to Athenian (Attic) Black and Red Figure Pottery & Three-Step Firing Process

Revitalize your understanding of a beautiful form of ancient Greek pottery and complex firing process before launching into famous artists and vibrant vases.

Attic Black and Red Figure Pottery

Athenian or Attic Black and Red Figure Pottery is a stylistic form of pottery-making that emerged between the beginning of the sixth century and end of the fourth century B.C.

It developed from earlier styles traceable back through Corinthian and Geometric painting” (Boardman 2001: 13, figs. 1-3; Freestone and Gaimster 1997: 41, fig. 4) (Oleson, 511) and is highly regarded for its artistic quality of the painted decoration and the exquisite detailing.

Painted pottery and vases were created in a variety of shapes and sizes based on their intended range of daily uses, such as storing and transporting wine and foodstuffs (amphorai), drawing water, drinking wine or water, and eating, in addition to special or ritual occasions, such as pouring libations (lekythoi) or carrying water for the bridal bath (loutrophoroi) (https://www.metmuseum.org/toah/hd/vase/hd_vase.htm).

(Diagram of pot shapes from British Museum)

Process (Pre-Firing)

1. Potters began with the clay, which is governed by the physical properties of the particles and minerals of surrounding soil, such as size, shape, and relationship with water according to its depositional environment. The terra cotta clay is a reddish-orange color by nature.

2. Potters shaped the body into a vessel or form of their choosing, such as oil flasks, bowls, or the most popular: vases on a potter’s wheel (manually turned by the potter or an assistant).

3. After the vessels were formed on the wheel, they were kept in a damp room until ready to be decorated.

4. Afterwards, potters polished vessels with burnisher (a hard smooth surface, like a rounded rock or modern-day wooden spatula) to soften the surface.

5. Potters applied a thin base coat of yellow ochre, which was brushed over the vessel to intensify the color of the clay body. Once the polish achieved a smooth finish and increased the luster of the glaze, the clay body was burnished again.

Paint was applied directly onto this firm semi-dry or "leather-hard" clay surface. Slip is painted onto the parts of the vessel that are intended to be black. Slip is a mixture of water and clay, it is really thin and fine and procured after levigation, when heavy or coarse minerals sink to the bottom. Slip is very important because it contains sillica quartz crystals, which become very close together during firing and sinter into a “glassy” surface that is impenetrable to oxygen. The term black “glaze,” is really just slip.

Artisans and painters could then start a preliminary sketch of figures, perhaps, using a thin pointed stick of charcoal or lead, in order to map out their vision and ensure that their design would fit on the curvature of the vessel. The charcoal usually faded after firing, but it was visible to the painter and served as a guide for slip, which was used to fill in the silhouettes of figures or forms. After sketching, artisans painted slip on or began to scrape.

Three-Step Firing Process

Noble suggests that the basic technique of producing black glaze/slip through a three-step firing process was known as early as the Middle Helladic Period (1900-1550 B.C.)

The ancient Greeks used a kiln heated by wood or charcoal in order to fire vessels and Ancient Attic potters used only one firing cycle. The chemistry of this process was rediscovered by Theodor Schumann in 1942. The following content is from Joseph Noble’s “The Technique of Attic Vase-Painting”.

Step 1: Oxidizing

“In an initial oxidising atmosphere, body and slip fired red, due to the formation of hematite, ferric oxide. A reducing atmosphere was then induced by closing the vents of the kiln and adding wood to the fire, which converted the iron oxide of the slip to magnetite, which is black. At the peak of the firing, in the range 850-1000 Celsius, the potash content of the slip, coupled with its very fine grain size, caused it to fuse into a dense black glossy layer which was essentially impervious to oxygen. As the wood burnt down, the vents were opened and the kiln atmosphere became oxidising once more. Due to its dense, fused condition, the slip remained black. However, the coarse clay of the body retained an open, porous structure throughout the firing, which allowed oxygen to diffuse in, converting the reduced iron oxide to the oxidised form, hematite. Depending upon the precise composition of the clay and the firing temperature, the body then gave a red or buff background to the black slip. (D. Williams 1997: 89; cf. Noble 1988) (Oleson, 504).

During the first phase, oxidizing, both the body and the glaze turn red.

Red ferric oxide (Fe2O2) is present in both the body of the vase and the unfired black glaze/slip. During the initial oxidizing phase, both the body and the glaze turn red. However, in the middle of the firing process, the oxidizing process can turn into a reducing atmosphere with the introduction of green wood or damp sawdust. Green wood is wood that has been recently cut and possesses a very high moisture content. Smoke, which is composed of carbon is emitted and the kiln becomes a carbon-rich environment.

Step 2: Reduction

In the reducing phase, the vase and the glaze turned black.

The kiln is closed to the outside supply of oxygen or air. This causes incomplete combustion of the green wood or wet sawdust and produces carbon monoxide gas (CO) instead of carbon dioxide gas (CO2), which would be developed during normal combustion. When the temperature reaches 800 celsius, the atmospheric condition is changed to that of a reducing atmosphere.

Carbon latches onto and unites with any oxygen it can find. In this case, it combines with part of the oxygen in the ferric oxide (Fe2O3) in the clay, turning into ferrous oxide (FO). This changes part of the carbon monoxide (CO) into the stable form, (CO2) and the red ferric oxide (FE2O3) into ferrous oxide, which is black. The reaction in this process is Fe20 + CO = 2FeO + CO2. Temperature is increased gradually during reducing, until 945 celsius is reached. It closely decreases to 875 celsius. Fire draws the oxygen out during phase 2.

A water vessel, water vapor, moisture from the pottery itself, or from the green wood or wet sawdust in the kiln produces a magnetic oxide of iron (Fe3O) which is an even blacker oxide of iron than ferrous oxide (FeO). The reaction in this process is 3Fe2O3, CO = 2FeO3 + CO2. If the firing cycle stops, the clay body of the vase and the glaze would be completely and permanently black. The wet sawdust or green wood is consumed and air is let in, changing it from reducing to oxidizing.

Step 3: Re-Oxidizing

(The porous body turns red, but the slip (black) does not re-oxidize into a red color because it sealed off its black iron oxide from contact with oxygen in the air. Therefore, it emerges from firing with a red base and black “glaze”.)

Attic pottery is usually concluded by a re-oxidizing phase. A small hole is opened and oxygen is then allowed to enter and interact with some of the black ferrous oxide (FEO) or magnetic oxide of iron (FE3O4), turning it back into the red ferric oxide (Fe2O3). Because the vase has a porous clay body, this readily allows for the change from black to ferric oxide and the body of the work turns red again. The areas with black glaze, composed of ferrous oxide (FEO) combined with the black magnetic oxide (FE3O4), however, do not re-oxidize at these temperatures and remains black. The black glaze does not re-oxidize (owing to the fineness of the particles making up the glaze). It becomes very dense and sintered (compacting a mass of material into solid) and doesn’t permit the re-entry of oxygen, so a chemical reaction does not take place. Re-oxidization occurs at at 875C.

If the temperature is raised above 1050 Celsius, the black oxides in the glaze and re-oxidizes to a red form and the black color vanishes. Noble’s tests postulate that the highest temperature to which the ancient pottery was ideally subjected to could not have exceeded 950-970 celsius (Noble 309).

The kiln required around 12 hours to cool down, after which the vases could be removed.

(Content from Noble, Joseph V. “The Technique of Attic Vase-Painting.” American Journal of Archaeology, vol. 64, no. 4, 1960, pp. 307–318. JSTOR, www.jstor.org/stable/501329.)

Result

Sources

Art Institute Chicago. “LaunchPad: Ancient Greek Vase Production and The Black-Figure Technique.” YouTube, YouTube, 15 Apr. 2013, www.youtube.com/watch?v=FpLPx_Akl7Y.

Brouwers, Josho. “Making Ancient Greek Vases - A Look at Red- and Black-Figure Pottery.” Ancient World Magazine, 30 Mar. 2018, www.ancientworldmagazine.com/articles/making-ancient-greek-vases-look-red-figure-black-figure-pottery/.

Department of Greek and Roman Art. “Athenian Vase Painting: Black- and Red-Figure Techniques.” In Heilbrunn Timeline of Art History. New York: The Metropolitan Museum of Art, 2000–. http://www.metmuseum.org/toah/hd/vase/hd_vase.htm (October 2002)

J.V. Noble, "An Overview of the Technology of Greek and Related Pottery" in ed. H. A. G. Brijdger, Ancient Greek and Related Pottery: Proceedings of the International Vase Symposium in Amsterdam, 12 -15 April 1984 (Amsterdam: Allard Pierson Museum, 1984): 34; Schreiber, Athenian Vase Construction: 53-6.

Noble, Joseph V. “The Technique of Attic Vase-Painting.” American Journal of Archaeology, vol. 64, no. 4, 1960, pp. 307–318. JSTOR, www.jstor.org/stable/501329.