Material Analysis

Case Study : "The Siren" (c. 1740), in the Coach Gallery, Palace of Versailles

It is often useful to understand what materials the artist used (e.g. pigments and paint media), for the safety of the artwork during conservation treatment. This is especially the case when treating complex layers of paint, lacquer or gilding. In many cases, analysis can also differentiate between original paints and later-applied restoration.

In the case of the sleigh called "The Siren," we assisted in the analysis of individual finish layers, to help determine which were original and to better protect them during conservation treatment. Whereas the figure of the siren at the prow was decorated with gold leaf, the sides of the sleigh were covered with silver leaf having transparent, colored glazes of red, green and yellow over the silver. The overall effect of the sides was that of a semiprecious stone having colored veins. The vehicle had been revarnished during maintenance, most likely in both the 18th and 19th centuries, and the later-appplied varnish had substantially darkened with age. Its safe removal (without affecting layers underneath) was a challenge.

Samples of the finishes, as tiny as a pinhead, were examined under the microscope with visible light, and under different types of UV light yielding fluorescence. In the slideshow above, a sample from the side of the sleigh (taken adjacent to an area of loss from flaking) is examined under the fluorescence microscope at 50x magnification. UV illumination reveals a series of layes that are undetectable under visible light.

Chemical Analysis of micro-samples

Fourier Transform Infrared (FTIR) micro-spectrometry provides general information on the composition of certain paints, and usually can characterize certain paint media (as oil, resin, or protein for example). To identify the elements composing metal leaf and obtain further information about inorganic pigments, which may go undetected by the FTIR analysis, either Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) analysis, or Scanning Electron Microscopy-Wavelength Dispersive X-ray analysis (SEM-WDX), can be done.

To identify organic dyes of glaze pigments and textiles, High Performance Liquid Chromatography (HPLC) can be used. We can help clients determine which analyses may be necessary to understand their work of art, whether it be for its conservation-restoration, long-term preservation, or simply to identify the historical techniques employed by an artist. We coordinate such analyses, conducted in the laboratories of our associates in either the USA or Europe, and provide our clients with reader-friendly summaries that explain the findings and their impact upon the conservation of their work of art.