Elizabeth La Duc
A nineteenth-century Italian marble tabletop featuring micromosaic scenes of Rome was the subject of technical study and conservation treatment. The tabletop, part of the collection of Historic New England, is elaborately decorated with two distinct techniques: inlaid colored stones, also known as commesso di pietre dure or Florentine mosaic, and micromosaics, an art form developed in Rome. The tabletop was in poor condition, having broken into four large pieces with many areas of loss along the breaks, and required extensive treatment before going on display in the recently reinterpreted Josiah Quincy House in Quincy, Massachusetts.
Pietre dure and micromosaics have not received much attention in the conservation literature, with the exception of research by the Opificio delle Pietre Dure, the conservation institution in Florence which itself grew out of the Grand Ducal workshops that made the finest examples of pietre dure. In order to remedy the shortage of information, the materials and methods of manufacture of these two techniques were investigated using both high-tech and low-tech means, including Fourier transform infrared spectroscopy, microchemical testing, photomicrography, and art historical research.
The treatment of the tabletop raised many questions regarding best practices. Traditional treatments, such as those practiced by the Opificio delle Pietre Dure, often involve filling losses with the same materials as the original – i.e. cut decorative stone and glass tesserae. The methods were neither possible, given the lack of appropriate materials, nor desirable, given the preference for distinguishability of replacement materials. Instead, losses to the pietre dure were filled with bulked and tinted epoxy. Innovative techniques were developed to replicate the complex appearance of colored stone as well as to increase reversibility. As an alternative to using glass or epoxy tesserae, the losses in the micromosaics were filled then inpainted using novel methods to replicate the complex appearance of the tesserae. In addition to these alternative treatments, some traditional practices were determined to be the most satisfactory and appropriate. After testing and discussion, methods such as using fine abrasives to polish out scratches and coating the table with wax to restore gloss and saturation were used to complete the treatment and prepare it for installation in a historic house museum.