A TECHNICAL NOTE ON NIELLO
R. Newman, J. R. Dennis, & E. Farrell
2 HISTORY OF NIELLO
THE NUMBER OF published analyses of niello remain few; consequently the history of the use of the different types is still not well known. A limited number of analyses were published by Moss in 1953;2 Schweizer has reported analyses of Byzantine niello;3 and Oddy et al. have recently published 18 new analyses.4 The analyses of 12 niello samples from nine mid-6th century Byzantine silver objects in the Research Library and Collection, Dumbarton Oaks, Washington, D. C., are reported in this paper.5
Copper niello has thus far been identified only on Roman objects (1st–4th century).6
Published analyses suggest that silver niello was used earlier than silver-copper or silver-copper-lead niello: silver niello has been identified on Roman objects from as early as the 2nd century,7 while mixed types have not been found on objects of earlier than medieval dates. However, classical and medieval treatises indicate that these mixed types were known as early as the silver niello. Pliny gives a recipe for a silver-copper niello,8 and the medieval treatise, the Mappae Clavicula, contains a recipe for silver-copper-lead niello.9 A summary of several recipes is given in Table I with the relative proportions of sulfides in each. The method of preparation normally involves mixing simple proportions of metals together and burning these with excess sulfur.
TABLE I COMPOSITIONS OF NIELLO FROM VARIOUS TREATISES
The earliest analyzed examples of silver-copper niello are of 6th-century dates. Oddy et al. found such a niello on a gilded silver Anglo-Saxon brooch,10 while Schweizer found such a niello on a 6th–7th century Byzantine silver object.11 Of the 12 samples we have studied from 6th-century Byzantine objects, six are silver-copper niello, with copper contents (estimated by emission spectrography) in the ranges 1–10% (one sample) and 10–15%(five samples). The remaining six samples were either relatively pure silver sulfide or silver sulfide with less than 1% copper. A summary of these 12 samples is given in Table II.
Silver-copper-lead niello has not been identified on objects of early medieval date. Schweizer found one such niello on an 11th–12th century Byzantine object, 12 while Oddy et al. found a sample on a 13th-century object.13