Recording industry term for a test pressing of a phonograph record. The acetate disc is created in the mastering stage of record production and is used to determine how the recorded material will transfer to disc. The disc provides a reference source for changes to be made to the recording, such as changing overall volume or adjusting bass and treble, to ensure it will transfer to a vinyl record as well as possible before the master disc, from which the actual records will be reproduced, is created.
An acetate record normally consists of an aluminum disc coated with nitrocellulose lacquer and doesn’t contain any actual acetate at all. They are sometimes made with cellulose acetate, which is also used as a film base in photography, and as a component in some adhesives.