Treatment of two sarcophagi, Etruscan Late Classical or Early Hellenistic:
September 2011
The first step is to carefully examine and document the physical condition of the sarcophagi. Important information, such as weak areas of the stone, crack patterns, level of staining, and previous repairs, is noted through a detailed study of the stone surface and substrate.
Conservators utilize a metal detector to identify metal rods used to pin a large break located across one of the sarcophagi lids. The exact location and length of the rods will be further clarified through the use of industrial X-radiography to be conducted onsite.
A birds-eye view of the lids is captured by elevating the camera eight feet above the sarcophagi and carefully clamping the camera onto a gantry beam.
The sarcophagi underwent restoration prior to their arrival to the Museum, likely shortly after their discovery in Italy in 1846. Examination of the condition (below, of a section of inscriptions) is critical to better understanding the extent of the previous restoration.
Through the use of analytical equipment, such as the Fourier transform infrared spectrometer and scanning electron microscope, Museum scientists are identifying the type of stones used to construct the sarcophagi. Once the materials are known, detailed compositional information may lead scholars to the area the stone blocks were originally quarried. Studies of the paint remnants found on the stone can also provide art historians with important information regarding the types of paints and decorative schemes used by the Etruscans.
Below is a back-scattered electron image of a cross-section of yellow crust from the narrower sarcophagus taken in a scanning electron microscope (width of field: 2.0 millimeters). The crust consists mainly of calcium carbonate, which has been altered to gypsum in places. Other mineral material has been incorporated into the crust. The pigment particles at the bottom are embedded in a fine-grained mixture that contains some clay and may be the remnant of a ground layer from the original painting.
Here is a magnified view of the area outlined in red above (width of field: 0.06 millimeters). The angular intermediate gray particles are grains of the pigment Egyptian blue. The small, bright white grain left of center is vermilion, particles of which are found scattered along nearly the entire length of the cross-section. Egyptian blue, on the other hand, is restricted to only two small areas in this sample.
Conservators test custom-formulated cleaning solutions to determine safe techniques that can be employed to reduce the decades of dirt and grime accumulation. Particular attention is given to developing a cleaning method that will not harm the stone, or the fragile passages of original paint.
Below is a detail of an area cleaned with cotton swabs and a mixture of de-ionized water, mineral spirits, and a non-ionic soap.
