A really obscure forgotten audio format: “Talking rubber”

While common magnetic tape uses very thin, plastic-coated iron oxide, “talking rubber” uses rubber impregnated with iron oxide. Iron oxide (a form of rust) is ferromagnetic, which means in the presence of a magnetic field, the electrons in the iron oxide magnetically line up and stay that way even after the magnetic field is turned off. This allows cassette tapes to create a “track” of magnetically aligned iron oxide when the electromagnet in a cassette recorder creates a magnetic field.

But with magnetic rubber, the iron oxide is actually mixed into the rubber material; the whole band becomes ferromagnetic, instead of just the coating. According to that Bell System Journal article, this “talking rubber” could be around 1/16 or 1/8 of an inch think, whereas magnetic tape was (even in the ’50s) already much thinner at 1/1000 of an inch thick.

More obscure audio formats!

18 Comments

  1. 2017-01-23 1:59 pm
    • 2017-01-23 2:35 pm
      • 2017-01-23 4:37 pm
        • 2017-01-23 8:23 pm
        • 2017-01-24 2:52 am
          • 2017-01-24 12:12 pm
  2. 2017-01-23 8:05 pm
    • 2017-01-23 8:36 pm
      • 2017-01-24 12:20 am
        • 2017-01-24 8:00 pm
          • 2017-01-24 8:16 pm
      • 2017-01-24 8:38 pm
    • 2017-01-23 8:48 pm
  3. 2017-01-23 8:39 pm
    • 2017-01-24 2:48 am
      • 2017-01-24 5:44 pm
  4. 2017-01-24 11:03 pm
  5. 2017-01-26 1:44 pm