Alnico magnets

  Before there were rare earth magnets, there were Alnico (Aluminum Nickel Cobalt) magnets.

  Flexible magnets, made by mixing ferrite magnet powders and synthetic/natural rubber binders were brand new in the mid fifties.

  They had been invented by the German company Max Baerman, Goodrich Rubber developed a way to make them in sheet form, specifically for refrigerator door seals.