Most discs recorded before 1948 have wider grooves (often referred to as "coarse" or "standard" grooves), were recorded using equalizations that differ from current standards, and are generally monophonic. They also require appropriate styli for optimal playback fidelity and to reduce disc damage along with equipment that can support the discs' diameters.
PlaybackĪll grooved disc media must be played back at the appropriate recording speed. Presently, playback equipment for this format is still being manufactured. They do not flex like vinyl, and they can break easily because they often do not have a reinforcing substrate like lacquered discs. Pre-World War I discs may be composed of more volatile materials and may require greater preservation attention. Risk Level Shellac-type 78s manufactured post-WWI are relatively stable and not considered especially vulnerable to age-related deterioration or inherent vice. Excessive surface damage and groove wear are generally identifiable on discs that have a dull surface, scratches, pits, and/or cracks. Types of surface contamination include: dirt, dust, mold, and other foreign materials, all of which can abrade or damage the grooves and diminish playback sound quality. Composition Shellac-based disc, with a variety of additional filler and additive materials Deterioration All grooved disc media is susceptible to warpage, breakage, groove wear, and surface contamination. Commercially pressed 78 disc labels are visibly pressed into the shellac, whereas most vinyl and lacquer discs are glued on. Shellac is often correlated with 10" 78s. They are typically played back at the following speeds: 30 rpm, 70 rpm, and 78 rpm. Shellac discs are most commonly one of the following sizes: 7-inch, 10-inch, 12-inch, and 16-inch. Originally known as Durinoid, shellac may contain other resins, plasticizers, and hardeners.
Paper substrate fibers exposed through chipped edge (under magnification).ĭates 1897 – late 1950s Common Size(s) 7" 10" 12" 16" (diameter) Description Shellac-type is a recorded sound format that consists of a coarse-grooved disc made of shellac resin with varying components, typically clay, slate, and limestone as filler, carbon black for color, and cotton fibers for strength. Paper substrate fibers exposed through chipped edge. Image courtesy of Aaron Coe, The Cutting Corporation.
#Little eva 33 rpm license#
Image by Flickr user Oliver Hammond, available under a Creative Commons Attribution-NonCommercial-ShareAlike license ( CC BY-NC-SA 2.0).ġ0" 78rpm shellac disc. Image by Flickr user Leo Reynolds, available under a Creative Commons Attribution-NonCommercial-ShareAlike license ( CC BY-NC-SA 2.0).Ĭommercially pressed 78 disc label. Shellac disc grooves are considerably larger than those of a microgroove vinyl LP.Ĭommercially pressed 78 disc label. Courtesy of the Danish Broadcasting Corporation. Image by Flickr user DRs Kulturarvsprojekt, available under a Creative Commons Attribution ShareAlike license ( CC BY-SA 2.0). Shellac discs are typically thicker than other discs.įrom this angle, the shellac disc's center spindle hole reveals that the disc has no substrate material. Although many discs will be found in these enclosures, they are not recommended for long-term storage and should be assumed to be acidic. Shellac 78 with original fiberboard sleeve.
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