Historical Painting Techniques, Materials, and Studio Practice

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Table 2. Unusual occurrences and constituents of smalt and blue enamel.

Source Accession Blue pigment Date

Number or enamel

BasohJi miniature 1.5.50-1953 smalt 1660-70

1.5.51-1953 small 1660-70

I.M.87-1930 small 1730-35

I.M.88-1930 smalt 1730-35

Bundi miniature 0.379-1889 small c.I770

Venetian jug 273-1874 enamel 1472-1525

tazza 5496- 1859 enamel late 15th C.

bowl C.170-1936 enamel 1521- 23

bowl C. I60-1936 enamel early 16th C.

bowl 5489-1859 enamel 1500-1600

S. German oil painting C.I.A. No 3021 small 15th - 16th C.

• lead from lead white pigment

t tin and antimony from yellow enamel applied over blue

* Courtauld Institute of Art, SEM-EDX analysis

EDXRF Analysis

Minor Trace

Pb' KCa Fe Co Ni Cu As

As Ph· KCa Mn Fe Co Ni Cu Zn Bi

As KCa Fe Co Ni Zn Ph Bi

As KCa Fe Co Ni Zn Pb Bi

Pb' KCa Ti Fe Co Ni Cu As

As KCa Mn Fe Co Ni Cu Zn Pb Bi Sr Sn

As KCa Mn Fe Co Ni (Au) Ph Bi Sr

As KCa Ti Mn Fe Co Ni Cu Ph Bi Sr

As KCa Mn Fe Co Ni Cu Zn Ph As Bi Sr (So Sb)t

As KCa Mn Fe Co Ni Cu (Au) Ph Bi Sr Sn Sb

Si K Fe Co Ni Pb. Bi

astery of Chora (Kariye Camii), Constantinople (1325-1 453 C.E.) (32, 33). It

is likely that the smalt derived from Middle Eastern and Near Eastern blue

glass.

The earliest known source of cobalt ore is Khashan, Persia; the Mesopota­

mians and Egyptians probably obtained it from there. This suggests that the

ore's coloring properties were already known to the Persians. Medieval Eu­

ropean glass was tinted with Damascus pigment or zaffre, the Arabic name

fo r cobalt oxide, again suggesting a Near Eastern source (34).

Cobalt oxide, known as sulimani, was imported into China from Persia in the

Tang period; by the fo urteenth century it was transported by sea from the

Persian Gulf via Sumatra. Muslim merchants residing in China influenced

ceramic designs; much of the blue and white ware was produced fo r the

Islamic market (35).

Cobalt blue glass and glaze was known from China to Western Europe and

yet throughout this period (3000 B.C.E. to ca. 700 C.E.) the most important

blue pigment was Egyptian blue, a fr it colored with copper, at its best rivaling

azurite but often appearing in paler turquoise shades. The terminal date is

circa 850 C.E. on a fresco in the church of San Clemente in Rome (36). It

seems unlikely that the secret of making Egyptian blue was lost to the

Romans during the turmoil of the Teutonic invasions, as glass and enamel

colored with copper continued to be made both in Italy and many other

countries.

In Europe there is an inexplicable hiatus in the use of blue pigments deriving

from glass from about 850 to 1490 C.E. The Venetians were making cobalt

glass by the mid-fifteenth century; the earliest references to smalt are by Le­

onardo da Vinci and Perugino in the 1490s (37). It has been identified on

an altarpiece (1493) by Michael Pacher (38). Cobalt was discovered in Saxony

in the mid-fifteenth century and fu lly exploited by around 1520. This may

explain the greater utilization of smalt in the sixteenth century (39, 40).

Cobalt ores combine iron with nickel and/or arsenic, the latter volatilized in

the smelting process. Cobalt was also obtained fr om the residue in the sep­

aration of bismuth (41). The metal oxides were fu sed with sand and potash

to produce zaffre (the Arabic name still being used) and sold to glassmakers.

During research on Indian miniatures, the author fo und smalt on one Bundi

example (ca. 1770 C.E., central India, Hindu). The pigment, not previously

identified on Indian paintings, contained cobalt, iron, nickel, and a little ar­

senic (Table 2) (Plate 13).

In a later project examining miniatures from the northern Hindu states, smalt

was fo und on fo ur miniatures from Basohli, a tiny state in the Himalayan

fo othills north of Lahore (42, 43). In one example (1660-1670 C.E.), smalt

was used to paint areas of the sky and Krishna's skin; the pigment contained

Historical Painting Techniques, Materials, and Studio Practice