At The Metropolitan Museum of Art a long-term project is currently underway for the renovation of the Greek and Roman Galleries. The resulting increase in gallery space will include a large courtyard, currently used as a public restaurant, to house classical sculpture. During the past several years, in anticipation of this expansion, the Museum acquired several ancient marbles.

As part of the scrutiny to which possible acquisitions are subjected, it is the responsibility of the Museum's conservation departments to evaluate evidence relating to the physical condition of a work of art, and from this to reconstruct its history. In the case of ancient marble statuary, the archaeological environment, as well as circumstances of display in antiquity and modern times, are important considerations. Human intervention, in the form of damages, wear, and in instances of reuse, repair, and restoration, can also be seen. An experienced eye is one of the conservator's most valuable resources, and frequently a significant amount of information can be gleaned from careful examination under magnification and ultraviolet light.

A recently acquired Imperial Roman portrait of a woman (Figure 1) can be used to illustrate just how the understanding of an object's current condition can aid in piecing together its history. As a starting point, evidence of original manufacture is considered. The consistent color and grain of the stone throughout the sculpture indicate that the head was carved from a single block of marble. The carving style on the front of the portrait differs from that on the reverse, where there is less detail, tool marks are still visible, and the marble surface is not as highly polished (Figure 2).

Whereas many examples of ancient Greek marble statuary survive with some original pigments, our knowledge of Roman polychromy is far more limited. With the aid of a stereomicroscope, several areas on the portrait can be noted where traces of color survived under soil accretions. The hair, the lips, and the irises and eyelids were all painted in shades of red or orange, while a series of regularly spaced lines, also red, denoted the eyelashes and eyebrows (Figure 3). The pupils were painted black.

Visual examination of the head could be profitably supplemented with instrumental analysis. X-ray fluorescence, energy-dispersive X-ray spectrometry (EDS), and polarized light microscopy were used to identify the pigments present. The reds and oranges are an iron oxide in the form of red ochre. The black is probably carbon, a conclusion based on the absence of any elements that could be detected using EDS. Traces of lead found in the areas of the lips and eyes suggest the use of red lead. It is possible that the extant pigments do not reflect the portrait's final appearance; red ochre, which is by far the most common pigment, could have been used in a ground layer onto which other pigments were applied.

Historic sources suggest that this type of portrait was most likely to have been displayed in an indoor environment, as a funerary monument or in another private context. This could explain the absence of ancient weathering that might have occurred had the piece been exposed to the elements for an extended period. The presence of tool marks on an otherwise finished work can signal that the stone was reworked at a later date, but in this case examination of the reverse of the head under ultraviolet light demonstrated that the surface appears as it did when the stone was buried. While in theory the marble could have been recut in ancient times, it is more likely that the unfinished quality of the work is an indication that the portrait was placed in a niche and not meant to be viewed in the round, a circumstance typical of Roman portraiture of this kind. The portrait was probably neglected or vandalized when the building in which it was housed fell into disuse, and damage to the nose and cheeks occurred before or at that time. When viewed under ultraviolet light, the fluorescence both in the damaged areas and on original, undamaged surfaces that were directly exposed to the burial environment is comparable.

Spread over much of the surface of the stone are root marks, which establish that the portrait was buried in fertile soil for an extended period (Figure 2). Although they look very similar, root marks are not actual roots, but mineral pseudomorphs that form as a result of contact between a plant and the stone. Calcium in the marble is leached by a caustic biological compound and over time is redeposited, replicating the form of the original root. Other compact mineral accretions are also scattered over the surface, especially along the woman's right jaw. While the authenticity of this portrait was never in doubt, it may be noted that fraudulently applied surface deposits tend to be more loosely adhered and less compact.

The portrait, once excavated, was cleaned of burial soil and, presumably, on this occasion much of the original polychromy was unintentionally removed. At some point, a sizable piece of stone was cut from the back of the head and reattached (Figure 4). That this alteration was made in the relatively recent past is clear, because under ultraviolet illumination the sawn edges around the join do not fluoresce, unlike the exterior surfaces that were in direct contact with soil. The color and grain of the marble, as noted earlier, are consistent throughout, and both pieces have similar accretions and root marks. Other evidence demonstrating that this is neither a replacement nor a repair necessitated by accidental damage lies in the fact that the fragment's join surface is fractionally smaller than the opposing break surface on the head. The loss of material corresponds to the kerf of the blade used to saw the stone. No indications for the use of a modern or ancient pin were visible in radiographs, suggesting that the section was reattached with an adhesive, although under ultraviolet illumination none was observed around the join. A possible motive for such an alteration remains obscure, but when the back of the head was sawn off the resultant fragment was retained, presumably under the assumption that it would be rejoined at a later time.

Although emphasis is often placed on high-tech methods of study, the value of careful visual examination should not be underestimated. This deceptively straightforward process, when combined with a solid knowledge of ancient techniques, the properties of the material in question, and an experienced eye, are invaluable in understanding the physical condition of ancient stone statuary.

The Portrait Head of a Woman was featured in Recent Acquisitions, A Selection: 2000–2001, MMA Bulletin 59 (Fall, 2001) p. 12, and is currently on display in the Museum's temporary Roman sculpture gallery.

Kendra E. Roth is associate conservator at the Sherman Fairchild Center, where she has worked on the Greek and Roman installation project since 1997. After completing internships at the Philadelphia Museum of Art and the Conservation Analytical Laboratories (Smithsonian Institution), she received her M.S. in art conservation from the State University of New York at Buffalo in 1996, and a postgraduate Certificate in Advanced Training from the Straus Center for Conservation at Harvard University in 1997. She has worked on archaeological excavations at Kaman Kalehoyuk and Kerkenes Dag.