Editing Acetate disc (section)

== Physical characteristics ==

Despite their name, "acetate" discs do not contain any [[acetate]]. They consist of an [[aluminum disc]] with a coating of [[nitrocellulose lacquer]] with acetone added to make a varnish. Glass was often used for the substrate during World War II, when aluminum was in short supply.<ref name="Preservation">{{cite web |url=https://www.loc.gov/folklife/sos/preserve1.html |title=Preserving Sound Recordings |website=[[Library of Congress]] |date=2005-04-28 |access-date=2008-04-16 |archive-url=https://web.archive.org/web/20080416203302/http://www.loc.gov/folklife/sos/preserve1.html |archive-date=16 April 2008 |url-status=live}}</ref><ref name="mcleod">[http://www.midcoast.com/~lizmcl/earlyradio.html ''Documenting Early Radio: A Review of Existing Pre-1932 Radio Recordings''] {{webarchive |url=https://web.archive.org/web/20120402112900/http://www.midcoast.com/~lizmcl/earlyradio.html |date=2012-04-02}}, [[Elizabeth McLeod]], 1988-9</ref> The production process results in a disc that is different in several ways from the vinyl records sold to customers at retail. Most noticeably, vinyl records are comparatively lightweight and flexible, while lacquers are rigid and considerably heavier because of their metal cores.

Lacquers commonly come in three sizes: {{convert|10|in|cm|0|adj=on}} discs for singles and {{convert|14|in|cm|0|adj=on}} discs for albums as well as {{convert|12|in|cm|0|adj=on}} discs for LP references and for 10" master cuts. The record's sleeve is typically nothing more than a generic cover from the manufacturing company and the disc's label is similarly plain, containing only basic information about the content (title, artist, playing time, and so on), which is usually typed but may be hand-written.

Although once produced in a wide range of sizes (from less than {{convert|7|in|cm|0}} to more than {{convert|16|in|cm|0}} in diameter) and sometimes with glass core discs, the examples most commonly encountered today are {{convert|10|,|12|or|14|in|cm|0}} in diameter. 

Blank discs were traditionally produced in several different grades, with the best and costliest grade featuring the sturdiest core, the thickest coating and the most perfectly flawless mirror-like surfaces. These top-quality blanks were intended for cutting the master discs that, once silver-coated, would be electrodeposited with nickel in order to electroform parts used in making stampers (negative profile metal moulds) for [[record press|pressing]] ordinary records. Lower-quality blanks were considered adequate for non-critical uses such as tests and demo discs. Lower-grade blanks were formerly made for home use by amateurs and may be very thin and flexible, may have a cardboard rather than a metal or glass base, and may have noticeably dull or slightly orange-peel-textured surfaces.

In addition to the usual central ''spindle hole'', there is traditionally at least one ''drive hole'' in the label area, meant to be engaged by a special pin that prevents the disc from slipping on the turntable during the recording process if the lathe does not have a vacuum turntable. Drive holes are often hidden by labels applied after the recording was cut, but they can usually be detected by careful inspection of the label or by holding the disc up to a light bright enough to penetrate the labels. Drive holes are no longer standard on lacquer masters, only on "dubs", because the additional holes can interfere with the electroforming process and professional mastering lathes use vacuum turntables that hold the workpiece (lacquer disc) in place with suction. One pump usually provides suction for both the turntable and the chip tube that pulls away the fine string of nitrocellulose lacquer removed by the groove-cutting stylus.

Acetate discs are made for special purposes, almost never for sale to the general public. They can be played on any normal record player but will suffer from wear more quickly than vinyl, since the lacquer does not have the same properties as that of vinyl.