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Applications in Art Conservation

Micro-Scan Services, Inc. offers microscopic fourier transform infrared spectroscopic analysis of both organic and inorganic components of art materials. Micro-Scan Services, Inc. is not a conservation laboratory, but it is an analytical services company specializing in sample isolation and preparation, followed by microinfrared spectroscopy. Our limiting sample size is about 10 microns in diameter, although good spectra have been obtained on particles as small as 5 microns. The analysis results in a full infrared spectrum (4400 to 660 cm-1) which can be matched against reference materials supplied by our clients. Some applications are described below:

The identification of previous varnish compositions on works that may have seen restoration in the past can lead to judicious choices of cleaning media and techniques. This is especially important in works that have seen previous restoration in the 20th century where the choices of materials have broadened. Tha analysis of the paint composition requires the removal of a microscopic sample for analysis. This can readily be accomplished by a skilled restorer with a fine scalpel and binocular microscope. An alternative method is to use a sharpened hypodermic needle to remove a tiny core from an area of interest. We can then embed the core in a casting compound, microtome the paint section, and analyze each layer. This provides a depth profile of the vehicle, and in some cases, the pigments and other fillers of the paint. Finally, the ground layer or base treatment frequently can be defined as well.
The analysis of organic materials in modern sculpture can be an aid to the correct replacement of broken or degraded portionsor can provide materials identity information on intact articles that will guide conservators in the proper specification of cleaning chemicals. In older sculptures, the composition of the object is generally well known, but restorations and repairs can add unknown materials that may not age gracefully and need removal or further treatment. The analysis of both the binder and the filler from these previous restorations can be carried out on microscopic samples.
The analysis of fibers is an ideal application for microinfrared spectroscopy. The technique is especially powerful for synthetic fibers, where the light microscopy techniques do not readily characterize the materials. In some cases, we can identify the types of dyes on synthetics and natural fibers as well as some stain residues. The size of the sample required for the analysis is usually one fiber about 20 microns in length. However, in the interests of easy transport and handling, we would prefer several lengths about 2 mm long.
Applicaions of microinfrared spectroscopy to paper conservationinclude the identification of fibers of fiber mixtures, the analysis of of original sizing or sizings and varnishes used in previous restorations, and the determination of the composition of stains. Most of these analyses can be carried out on microscopic sammples scraped from the edge or the backside of a document. Additional applications include the identification of ink binders and pigments. The results of these analyses can be used not only for guiding restoration efforts, but can provide confirmation of document authenticity.

Some applications may not be mentioned because of our unfamiliarity with the entire range of conservation activities. If there are problems that you feel could be solved by the application of micro-FTIR, please contact us, describing the analytical question; we will advise you of the suitability of our analytical methods.

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