Page 253 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

silver, and lead sulfides. Niello has a long history of use as a decorative inlay and was often used
as contrasting black areas of design with silver. It was usually used in champlevé style, as was
common with enamels, where the object to be decorated was cut or engraved with a design, and
the channels or lines were filled with niello. The object would be heated to fuse the niello into a
compact mass and then finished by grinding and polishing. In his De diversis artibus, Theophilus
(i96i) provides detailed instructions on how to apply niello by filling goose quills with the fine
particles and then tapping them into position on the engraved foliage before carefully heating the
object in burning coals until the niello has melted into position.
Niello decoration was widely used on Bronze Age objects, often of gold; examples are
known from many different cultures, including European, Islamic, and ancient Indian. Silver
vessels inlaid with niello are known from the late Hellenistic and early Roman periods, with
many examples from the third century and later. Some analyses show that pure silver sulfide
was used to make Roman niello (Ogden 1982). Unlike the mixed sulfides of copper and silver,
i
silver sulfide will decompose f heated, so it must have been burnished into position while being
heated just enough to make the compound plastic. Eggert, Kutzke, and Wagner (1999), however,
question whether these sulfides would really behave in a plastic fashion, like glass, below their
melting point and wonder f some kind of flux might have been used. Ogden adds that on a later
i
Roman ring there had been some diffusion of silver into the surrounding gold, suggesting the
use of a mixed sulfide. Black copper sulfide inlays in some first-century C.E. Roman buckle
plates that had been recovered from Hod Hill, Dorset, England, were not fused into position,
however, and may have been inserted as precut inlays.

Niello recipes Pliny gives the following recipe for making the mixed copper-
silver sulfides:

The method adopted is as follows: with the silver is mixed one third its amount of the very
fine Cyprus copper called chaplet-copper and the same amount of live sulphur as of silver,
and then they are melted in an earthenware vessel having its lid stopped with potters clay;
the heating goes on until the lids of the vessels open of their own accord. 9

Niello began to be frequently used from the beginning of the Christian era. More recipes
that may refer to the fabrication of niello are found in the Leyden Papyrus (Caley 1926), a medi­
eval manuscript with content that may go back many centuries. Recipe 36 of the document
refers to "black asem," which may mean niello. The recipe starts with copper, tin, lead, and
sometimes mercury, which are placed in a crucible. To make black asem, two parts of "normal
asem" (probably copper and silver) are mixed into the contents of the crucible along with four
parts of lead; the mixture is then melted with three times as much sulfur.
Interestingly, another medieval niello recipe recorded by Theophilus (196i) calls for an ele­
mental composition that is very similar to Pliny's mixture. Theophilus's recipe is complicated

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