An aluminium disc (or aluminum disk in North America) is a disk made out of aluminium and is used as a transcription disc in magnetic recording media, specifically early radio recordings.[1] Aluminium discs are also used in hard disk (as "platters"), shock tubes, and other manufacturing processes.
Originally, aluminum disc recordings were produced by scratching an imprint directly onto the aluminum surface. Such recordings were very durable, but could not be re-recorded.[2] In 1934, the Pyral Company in France, and the Presto Corporation in the United States, independently created the acetate disc by applying a layer of lacquer onto the aluminum disc.[1] This made re-recording possible, but over the years some recordings have been lost due to the acetate drying up and flaking off.[2]