Chemical Composition: ICP-MS/AAA data from sample, Bronze:
Cu, 86.7; Sn, 12.79; Pb, 0.03; Zn, 0.007; Fe, 0.15; Ni, 0.28; Ag, 0.05; Sb, less than 0.02; As, less than 0.10; Bi, less than 0.025; Co, less than 0.005; Au, less than 0.01; Cd, less than 0.001
J. Riederer
Chemical Composition: XRF data from Tracer
Alloy: Bronze
Alloying Elements: copper, tin
Other Elements: lead, iron, arsenic
K. Eremin, January 2014
Technical Observations: The patina is thin and dark brown. The surface is partially covered with a modern black resinous skin that has imbedded sand particles.
Portions of the proper right side of the plaque including both corners are broken off and lost, as are the top of the figure’s proper right wing and a lock of hair behind the diadem. A section of metal projecting at a right angle from the top edge of the back of the plaque is missing, and the projecting stub is twisted upward. The break edge of the plaque is distorted, with the lower corner twisted down and toward the back. The metal has a variety of surface textures; it is very smooth on the face and hair, and there is moderate to severe pitting elsewhere. The frame and panel are particularly deeply pitted. No green corrosion products were found, even in the recesses of the deepest pits. The center of the diadem has a slightly raised circular area that is somewhat more metallic in color, which suggests that the metal has been reworked; perhaps an element has broken off in that area and was leveled and smoothed. The bottom of the frame under the left breast has a 2.5-cm area of lighter, recently retoned patina that fluoresces quite differently under ultraviolet light compared to the rest of the object.
The plaque was cast in one piece using the lost-wax technique. A vertical wax drip is visible on the reverse of the remaining upper corner. The bust is hollow, and the core is intact. The backplate and frame were probably modeled directly in wax. The bust could also have been modeled directly, although it is more likely to have been cast in wax from a mold, with details restated or added in the wax, then attached to the backplate. A somewhat irregular 1.8-cm hole in the backplate behind the bust reveals core material that includes a piece of clay that resembles red brick in a matrix that is stained with brown and green corrosion and contains carbonized material. The pupils appear to have been punched in the metal, while the iris appears to have been drawn in the wax using a compass and possibly reinforced with later work in the metal. The details of the feathers could have been formed in either the wax or the metal. There are rectangular chaplets visible on the proper right cheek, proper left breast, and on the back of the plaque 13.8 cm above the hole in the core area.
The thicker black resinous skin with sand particles imbedded in its surface fills much of the interstices of the modeling and also covers all of the break edge surfaces, making it clear that this coating was applied after the damage occurred. The back of the relief is similarly coated, but it is thinner there and has very little imbedded sand. The complete absence of bronze corrosion products and burial accretion, even under the coating where examined, suggests that the plaque may have been electrolytically or acid stripped before the application of the black coating. The lighter brown appearance of the thin patina in some areas may simply be a function of the relative thickness of the applied black coating. Previous examinations of this object by W. J. Young and A. Beale refer to a number of the above mentioned features, as well to carbonized particles visible under high magnification in the black coating, which led them to conclude that the relief had been in a fire (1), but the presence of these particles could not be confirmed in the present examination.
NOTES:
1. See G. M. A. Hanfmann, “A Roman Victory,” in Opus Nobile: Festschrift zum 60. Geburtstag von Ulf Jantzen, ed. P. Zazoff (Wiesbaden, 1969) 63-67.
Tony Sigel (submitted 2001)
