Natural Science in Archaeology

210 9 Pigments and Colorants
Evidence confirms that iron oxide pigments were used by many societies
to decorate ceramics as early as the Neolithic Period. Later, the ancient Greeks
advanced this art to a new level. Clay slips containing iron oxide compounds were
used to produce the famous “black figure” ceramic ware. The technique, which was
perfected by 500 BCE, involved highly advanced skills in pyrotechnology. Iron
oxide slip normally fires to dark red in a kiln with an oxidizing atmosphere. The
Greeks learned to produce a reducing atmosphere by limiting the amount of oxygen
entering the kiln and by firing the kiln with green wood to yield carbon monoxide.
Under these conditions, the painted and unpainted areas of the ceramic turn black.
Oxygen was again briefly permitted to enter the kiln chamber at the end of the firing
cycle, thus causing the unpainted areas to return to a red color (Flight 1989).
The Greek scholar Theophrastus (ca. 372–287 BCE) categorized pigments as
being either earth, sand, or powder. He considered “ochre” and “ruddle” (sintered
ochre) to be earth (De Lapidibus 8.53). Although Theophrastus probably grouped
chemically and mineralogically different compounds together, “earth” pigments
certainly included iron oxides. According to Theophrastus, the Hellenistic Greeks
obtained ochre from Cappadocia (central Turkey), but the best ochre came from the
island of Keos. Ochre was frequently associated with gold, silver, copper, and iron
mines (De Lapidibus 8.51ff).
Another ancient Greek writer, Dioscorides (ca. 40–90 CE), recommended Egypt
as the best source for red ochre (Lucas 1989). The shift from Cappadocian to Egyptian
sources may reflect a change in trade routes and commercial influence. Perhaps
this was the result of the growing political influence exerted by the city of
Alexandria.
Pliny (23–79 CE) rated the red ochres of Egypt and Africa as “the most useful for
builders” since “they are most thoroughly absorbed by plaster” (Pliny, N.H. 35.15).
He noted the association of “red ochre” with iron mines. He also described methods
of altering red ochre by burning “in new earthen pots with lids stopped with
clay. The more completely it is calcined in the furnaces the better its quality” (N.H.
35.16). An example of the use of red ochre in northern Jordan during the Byzantine
Period is shown in Fig. 9.1.
Despite the detailed information offered by Pliny, it is obvious that he often
confused iron and lead pigments. He identified the compound called “ceruse” as
being “manufactured from lead and vinegar”. Pliny further stated that this compound
could be made by “calcinating yellow ochre which is as hard as marble and
quenching it with vinegar” (N.H. 35.19–20). This example again emphasizes that
the ancients identified pigments based on subjective characteristics, including color.
“Ochre” or “ceruse” could consist of a number of similarly colored, yet chemically
different, mineralogical compounds. Note that the modern use of the word ceruse is
for the compound (PbCO 3 ) 2 ·Pb(OH) 2 , which is used chiefly in paints and putty. The
name of the mineral cerussite, PbCO 3 , is derived from the ancient Greek word for
lead carbonate, which became cerussa in Latin.
According to the Roman architect Vitruvius (ca. first century CE), yellow ochre
could be found in many places throughout Italy. However, the previously favored