ASM Basket Research Benefits Museum Collections Worldwide
By Darlene Lizarraga
The conservation of American Indian basketry has been a passion for Arizona State Museum Conservator Dr. Nancy Odegaard since she was hired to conduct a survey and design a conservation plan for the Peabody Museum’s (Harvard) collection in the 1980s.
Through that project, she, along with colleagues Ron Harvey (Tuckerbrook Conservation/Maine) and Dale Kronkright (Georgia O’Keefe Museum/New Mexico), developed new approaches to cleaning the delicate surfaces of woven fiber objects.
Dental vacuums proved ideal for eliminating dust and dirt from the delicate surfaces without disturbing the fibers. Odegaard also revolutionized the standard practices of repairing tears and breaks by introducing the use of consolidated strips of Japanese tissue paper strategically placed to support the woven elements. These techniques, unheard of in the 1980s, are still taught today in graduate conservation programs and used in museums worldwide.
One of the reasons Odegaard chose to bring her professional skills to Arizona State Museum in 1983 was because of its unparalleled basket collection. It has been her dream since that time to consolidate ASM’s collection, to place it in a stable storage environment, and to share it more widely with the public.
Now, 30 years later, a $400,000 grant from Save America’s Treasures has Odegaard and ASM on the path to making that dream finally come true. The museum is in the midst of raising an additional $500,000 so that it can construct a climate-controlled storeroom and new interpretive space for the vast collection of woven wonders—some 25,000 objects.
In the meantime, Odegaard along with colleagues, students, staff, and volunteers, are working on three new techniques for researching and preserving basketry and fiber objects.
UA PhD candidate Molly McGath worked with Odegaard and long-time conservation volunteer Dr. Werner Zimmt to evaluate the impact and effectiveness of calcium hydroxide nano-particles to preserve archaeological cordage. The approach uses nano-particles as a buffer to protect cellulosic materials from acid hydrolysis (the destructive breakdown of fibers), thus preserving structural integrity and therefore extending the life of delicate fibers indefinitely. The challenge for McGath was not only to synthesize the nano-particles but to successfully apply them within the fibers. Testing on non-artifact pieces of cordage first, she used attenuated total reflectance–Fourier transform infrared spectroscopy and scanning electron microscopy, along with tensile testing, pH testing, and artificial aging, to evaluate the treatment. Shake table tests indicated positive effects on artificially aged samples, while also identifying the impacts of different container types on long-term structural stability.
The team will soon experiment on actual archaeological specimens from the museum’s collection. This project was funded by the National Center for Preservation Training and Technology.
A collaboration between Odegaard and Dr. Pamela Vandiver, professor in the University of Arizona’s Department of Materials Science and Engineering, has resulted in xeroradiograph images of ancient sandals in ASM’s collection. Using a standard X-ray cabinet to irradiate a sandal on a uniformly charged selenium plate, it was then processed in a xeroradiograph machine. The resulting imprint formed a charge distribution on the plate that attracted toner particles in a way similar to photocopying. A dry paper image was then produced. This technique is non-destructive and affords a clearer image than standard X-rays. Details of plant fibers and of weave technology are particularly sharp, and are therefore better for analysis.
Odegaard’s conservation team is also experimenting with solid particles of dry ice “snow” on baskets in need of cleaning. Odegaard and Zimmt got the idea after learning of the snow’s use in cleaning astronomical mirrors. The particles safely remove dust, soot, and other contaminates from delicate surfaces without causing scratches or other damage. Dry ice snow is made when pressurized carbon dioxide (CO2) is allowed to expand adiabatically (without heat transfer) into a gas. As the temperature drops, some of the gas solidifies into small particles, or snow. The sprayed particles sublime (change from solid to gas without becoming liquid) rapidly, surrounding each one in an envelope of gas. The dry, non-conductive, non-abrasive, non-toxic jet of CO2 snow pushes away the unwanted contaminants and leaves no residue because the particles never come into direct contact with the surface of the object being cleaned.
As with all the conservation protocols developed in Odegaard’s lab over the years, these will no doubt be translated into multiple languages and taught as standard operating procedure in conservation programs and used in museums around the world.