SOME IMPROVEMENTS IN THE STUDY OF CROSS SECTIONS
JIA-SUN TSANG, & ROLAND H. CUNNINGHAM
1. 10% KOH is added to the sample, and it is allowed to hydrolyze overnight. The solution is neutralized and dimethylformamide-dimethylacetal is added as the methylation reagent. This derivatization reagent can be obtained from Pierce Chemical Company under the name of Methyl-8. A 0.32 mm i.d.× 30M DB-1 (bonded polydimethylsiloxane) coated fused silica capillary column is used for the sample separation by GLC.
2. The derivatization procedures used here are those of the PICO-TAG system developed and supplied by Millipore Corporation. A reversed phase C-18 column kept at 41°C is used with a ternary separating solvent system of water, acetonitrile, and sodium acetate buffer (pH 6.4). The solvent mixture follows a gradient function supplied by Millipore.
3. Papillon et al. (1988) report that they prepared 100-micron microtomed sections for analysis. The paint sample was first embedded in epoxy, then cut on a microtome using a diamond knife. No step-by-step information is given in the abstract concerning the preparation of the thin sections. We became aware of this paper in August 1989. Our first report of the techniques we developed was submitted to the American Institute for Conservation in October 1988 and reported at the 17th annual meeting of AIC in June 1989. We have independently developed a thin sectioning system but have embedded our samples in polyester and sectioned them with a carbon-coated steel knife. We were able to achieve our goal of preserving the integrity of the microtomed section for binding media studies as well as the pigment identification. Our system also can section the sample much thinner than 10 microns if necessary. Gay (1970) reported that a 40–80-micron thick-sample was cut using a small manual microtome. The sections were then used for microchemical analyses. No detailed information on how to prepare the sample is given, and no information is provided on the analytical instruments used.
Baker, M., D.vonEndt, W.Hopwood, and D.Erhardt. 1988. FTIR microspectrometry, a powerful conservation analytical tool. AIC preprints, 16th Annual Meeting, American Institute for Conservation, Washington, D.C.1–13.
Erhardt, D., W.Hopwood, M.Baker, and D.vonEndt. 1988. A systematic approach to the instrumental analysis of natural finishes and binding media. AIC preprints, 16th Annual Meeting, American Institute for Conservation, Washington, D.C.67–84.
Gay, M. C.1970. Essais d'identification et de localisation des liants picturaux par de colorations specifiques sur coupes minces. Annuales, Laboratoire de recherche des musčes de France. 8–24.
Johnson, M., and E.Packard. 1971. Methods used for identification of binding media in Italian paintings in the 15th and 16th centuries. Studies in Conservation16: 145–64.
Meilunas, R. J., J. G.Bentsen, and A.Steinberg. 1990. Analysis of aged paint binders by FTIR spectroscopy. Studies in Conservation35:33–50.
Papillon, M. C., E.Martin, R.Lefevre, and J.Philippon. 1988. Analytical transmission electron microscopy as applied to ultra thin sections of paintings by two Italian primitives. 2nd International Conference on Non-Destructive Testing, Microanalytical Methods and Environment Evaluation for Study and Conservation of Works of Arts, Rome: Istituto Centrale Per I1 Restauro II/15-1–II/15-15 (abstracted in Art and Archaeology Technical Abstracts 1989, 26–613).
Plesters, J.1956. Cross-sections and chemical analysis of paint samples. Studies in Conservation2: 110–57.
Raehlmann, E.1910. Uber die maltechnik der alten. Berlin:
Reffuer, J. A., J. P.Coates, and R. G.Messerschmidt. 1987. Chemical microscopy with FTIR microspectrometry. American Laboratory, (April): 86–92.
Tsang, J. S., N.Ravenel, J.Berstein, and S.Odell. 1990. The conservation of the 100,000th Steinway piano. In Cleaning, retouching and coatings: Technology and practice for easel paintings and polychrome sculpture, ed.J. S.Mills and P.Smith. London: International Institute for Conservation of Historic and Artistic Works. 52–55.
Wolbers, R. C.1988. Aspects of the examination and cleaning of two portraits by Richard and William Jennys. AIC preprints, 16th Annual Meeting, American Institute for Conservation, Washington, D.C.245–60.
SOURCES OF MATERIALS USEDBEEM molds
Ted Pella, Inc., P.O. BOX 510, Tustin, Calif. 92681
Buehler Castolite embedding resin;, Buehler Isomet saw; and Buehler Minimet grinder
Buehler, Microstructural Analysis Division, 41 Waukegan Rd., Lake Bluff Lake Bluff, Ill. 60044Methyl-8
Pierce Chemical Co., P.O. Box 117, Rockford, Ill 61105PICO-TAG system
Millipore Corp, 34 Maple Street, Milford, Mass. 01757
JIA-SUN TSANG is a 1985 graduate of the University of Delaware/Winterthur Conservation Program. She was with the National Gallery of Art in Washington, D.C., from 1984 to 1987 before joining the Conservation Analytical Laboratory, Smithsonian Institution, in 1988 as paintings conservator. She was a specialist in clinical chemistry at the Medical College of Ohio, Toledo, Ohio, from 1974 to 1980. Address: Conservation Analytical Laboratory, Museum Support Center, Smithsonian Institution, Washington, D.C. 20560.
ROLAND H. CUNNINGHAM attended the New York University Conservation Program from 1965 to 1969 and served as chief paintings conservator for the Wadsworth Atheneum, Hartford, Connecticut, from 1971 to 1981. Since 1982, he has been senior paintings conservator at the Conservation Analytical Laboratory, Smithsonian Institution. Address: Conservation Analytical Laboratory, Museum Support Center, Smithsonian Institution, Washington, D.C. 20560.