A TRANSLUCENT WAX-RESIN FILL MATERIAL FOR THE COMPENSATION OF LOSSES IN OBJECTS
SUSANNE GÄNSICKE, & JOHN W. HIRX
. The term “wax” in “wax-resin” is used throughout the article in reference to ethylene acrylic acid copolymer (EAA). “Wax” is a rather loose term applied to a variety of substances consisting of hydro-carbons and sharing a number of characteristics such as waxy feel. Furthermore, most of them are relatively solid at room temperature, liquefy with increasing temperatures, and will solidify when cooled again.
. Burke has observed that some of the earliest samples he used have yellowed, a process he attributes either to lack of an antioxidant or to overheating at the time. He also subjected samples of the wax-resin to accelerated aging and then separated PVAC from EAA by melting. He noted that it appeared the PVAC component in fact had yellowed. Based on this observation, Union Carbide recommended adding a cycloaliphatic epoxy resin (ERL–4221) as a stabilizer to the PVAC. Samples of wax-resin prepared with this additive do not seem to have yellowed over 10 years. Burke has continued to use the epoxy resin as an antioxidant substitute for Irganox when he wanted to manipulate the hardness of the wax-resin. The cycloaliphatic epoxy resin is a liquid; Irganox is a solid. The inclusion of the epoxy resin results in a flexible wax-resin material. The addition of Irganox results in a material that is hard. The addition of either antioxidant is the same: 0.5% by weight. Burke is exploring other conservation applications of the EAA copolymers.
. Feller published a grading system for conservation materials and their expected photo-stability based on the blue-wool test using the International Standard Organization R105 blue wool standard 6 for photochemical stability, in which the degree of fading of a sample of blue wool has been quantified. Under most conditions, conservators prefer to use a class A material, which, based on annual museum light levels, should last for 100 years or more or suffer no more than 20% loss of its essential properties.
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SOURCES OF MATERIALSPolyvinyl acetate resins PVAC AYAA and AYAC
Union Carbide Corp., Specialty Chemicals and Plastics, Old Ridgebury Road, Danbury, Conn. 06817Ethylene acrylic acid copolymers A-C 540 and 580
Allied Signal Corp. A-C Performance Additives, P.O. Box 2332, Morristown, N. J. 07962–2332Irganox, antioxidant and thermal stabilizer
Ciba-Geigy Corp. Seven Skyline Dr. 3, Hawthorne, N.Y. 10532–2188Mylar, polyester film
Conservation Materials, Ltd. P.O. Box 2884, Sparks, Nev. 89431Novus Plastic Polish 2
Novus, Inc., 10425 Hampshire Ave. So., Minneapolis, Minn. 55438Epo-Tek 301–2
Epoxy Technology, Inc., 14 Fortune Dr., Billerica, Mass. 01821Pliacre Epoxy Putty
Philadelphia Resins Corp., 20 Commerce Dr., Montgomeryville, Pa. 18936Milliput Superfine Epoxy Putty
Milliput Corp., Unit 5, The Marion, Dolgellau, Mid Wales LL40 1UU, United Kingdom
Röhm and Haas, Independence Mall West, Philadelphia, Pa. 19105
SUSANNE GÄNSICKE has been an assistant conservator in the Department of Objects Conservation and Scientific Research at Museum of Fine Arts, Boston, since 1990. In 1987 she received a certificate in archaeological conservation from the Römisch-Germanisches Zentralmuseum, Mainz, Germany. She then served an advanced-level internship at the Museum of Fine Arts, followed by an Andrew W. Mellon Fellowship in Objects Conservation at the Metropolitan Museum of Art. She has worked as site conservator at the New York University Apis Expedition at Memphis, Egypt, and at the BMFA Expedition at Gebel Barkal, Karima, Sudan. She is particularly interested in the technical study of ancient Egyptian and Nubian material culture. Address: Objects Conservation and Scientific Research, Museum of Fine Arts, 465 Huntington Ave., Boston, Mass. 02115.
JOHN W. HIRX is currently a research assistant in the Conservation Center of the Los Angeles County Museum of Art, where he pursues research on the preservation of archaeological and decorative silver. He was formerly a contract conservator at the Brooklyn Museum, treating the Egyptian collection prior to a reinstallation of the newly renovated galleries. Address: Conservation Center, Los Angeles County Museum of Art, 5905 Wilshire Blvd., Los Angeles, Calif. 90036.