Dawn MP Wallace, Richard Barden, Janet Douglas, Dr. Gwénaëlle Kavich, Dr. Alba Martin Alvarez, Dr. Regina Baglia, and Mary Ballard
The National Museum of American History’s Ruby Slippers, the beloved shoes worn by Judy Garland in the 1939 classic film The Wizard of Oz, have been on display at the Smithsonian Institution since 1981. In 2016 their conservation, preservation, and long term display became the focus of the Smithsonian’s second Kickstarter campaign. This successful campaign funded research into their history, use, and construction, an in-depth assessment of their materials and condition, and identifying off-gassing degradation products. This analysis guided the Slipper’s treatment, and the design and construction of a display case with optimal environmental (temperature, humidity, light, oxygen) conditions. The shoes are comprised of at least 12 materials which have undergone various types of deterioration, some of which occurred during filming and others by natural degradation processes. The Slippers were created from commercially available pumps that were dyed, painted, and then adorned with sequins, bows and beads. Of particular interest are the sequins, consisting of a gelatin core with a red cellulose nitrate coating, which give the slippers their iconic ruby appearance. Some of the sequins appear transparent ruby red, while others are faded, opaque, have fractured surfaces, and coating losses. They are susceptible to changes in humidity, temperature, light, and chemical degradation.
Micro-X-ray fluorescence spectroscopy (μ-XRF), micro–Fourier transform infrared spectroscopy (μ-FTIR), polarized light microscopy (PLM), and scanning electron microscopy – energy dispersive X-ray spectroscopy (SEM/EDS) were used to identify the various materials used in the construction of the Slippers. A protocol to identify and monitor for volatile organic compounds included the analysis by solid phase micro-extraction gas chromatography/mass spectrometry (SPME-GC/MS) in parallel with Ormantine diffusion tube analysis. Rhodamine B was identified as the major colorant on the sequin coating using high performance liquid chromatography – diode array detector – mass spectrometer (HPLC–DAD–MS). This informed the creation of a VIS spectrophotometric library used to determine the most aesthetic LED light combination providing a spectral range that complements the light reflected by the slippers, as well as the optimum spectra to slow the deterioration of the materials.