MCI Project Summaries 2008 - Smithsonian Institution

MCI 6188 “Lacquer” Recording Discs: Material Characterization and
Display Guidelines
MCI Staff: Jia-sun Tsang, Rebecca Gieseking, Mel J. Wachowiak, Judy Watson
This preservation project seeks to find proper guidelines for the long-term display of
Woody Guthrie’s renowned 1944 record “This Land is Your Land”. The purpose of the visual
examination and instrumental analysis is to acquire information about the lacquer disc materials
for the continuous expansion of museum accession records as well as for ensuring the long-term
stability and preservation of Woody Guthrie’s disc.
A thirteen inch 1943 record produced by the same manufacturer for material
identification was selected. Closer examination of 1943 lacquer disc with microscope – scanning
electronic microscope (SEM) and Fourier Transform Infrared Spectrometer with Attenuated
Total Reflectance (FTIR-ATR) and Fourier Transform Infrared Spectrometer with microscope –
revealed that this record is most likely made of shellac mixed with fibers, fillers and carbon
black pigments. The first shellac discs date from the early 1900s, gaining popularity in the 1930s
and 1940s. After WWII, resins such as Vinsol, Valite, Vynil chloride acetate, and other
commercial resins replaced organic shellac as a main binder. Based on appearance, analysis, the
1944 disc is most likely made of shellac mixed with fiber, fillers and carbon black pigments.
Shellac discs are considered moderately stable. The instability of shellac discs is related
to high humidity and high temperature, mechanical deformations, and dust and dirt. In addition,
shellac can be easily extracted by common organic solvents and dissolved by ethanol and
isopropyl alcohol. Heat can cause deformation due to shellac’s low softening point. Acid and
alkaline can cause decomposition. In proper storage environments, shellac discs suffer a slow,
progressive deterioration where they become extremely brittle and fragile. Shellac discs should
not be handled with bare hands. Oil and perspiration from bare hands can damage discs, thus
making it imperative to wear lint-free cotton gloves or nitrile gloves. Recommended
environmental parameters for storage conditions and long-term exhibition of shellac disc, which
are established by music recording preservation community, are 5 o C to 10 o C temperature and
30% ± 5% relative humidity. To avoid warpage the disc should be displayed flat, on a slight
angle for proper viewing, and on an archival grade platform with proper ventilation equally
distributed to both sides of the disc. The recommended light level is a 10-15 foot candle. The
display case should have ultraviolet protection.
Results of this investigation not only offer an opportunity to identify the chemical
composition of Woody Guthrie’s “This Land is Your Land,” but it also offers insight to a green
plastic. This disc is made with non-petroleum based resin from bugs and renewable fibers and
stiffeners such as wood flour, flax, and other cellulose based fiber fillers. The development and
natural aging behavior of shellac lacquer, an early thermosetting plastic, could offer a historical
perspective to the current trends in the plastic industry in its pursuit of green plastic and in its
effort to reuse and recycle existing plastics with the strengthening wood fibers as wood plastic
composites.
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