Magnetic media can be used to record and store numeric and textual information, sound, motion and still images. common formats include:
- Hard disk drives (HDD)
- Floppy discs/diskettes.
- Audio reel to reel and cassette tapes.
- Video and computer tapes.
Magnetic Tape is referred to as ferromagnetic recording material, capable of being magnetised when placed in a magnetic field. There are many different formats of magnetic tape such as U-matic, VHS, S-VHS, 8mm, and Betacam (video) and many varied media composing them – iron oxide, chromium dioxide, barium ferrite, metal particulate and metal evaporated (ME). The main components of magnetic tape are the substrate and binder.
Structure of magnetic tape. Image: http://www.clir.org/pubs/report/pub54/2what_wrong.html
The top coat or binder layer functions as a carrier for the recording material, responsible for storing the magnetic signal written to it. It consists of magnetizable particles, suspended in a polymer binder. This binder, usually consisting of a polyester urethane resin holds the magnetic particles together and fastens it to the substrate.
Other components of a top coat layer that facilitates movement through a player:
- Lubricant: reduces friction and therefore the tension needed to facilitate play through a machine.
- Head cleaning agent can reduce clogs and therefore dropouts whilst the tape is playing.
- Carbon black reduces static charges, which may attract debris to the tape.
The substrate or base material acts as a support for the top coat, which would be too thin to exist autonomously. Its uniform surface reduces distortion, friction and dissipates any static charge.
In most cases the base is made from a polyester and packaged in a tape or disk form eg video/audio cassettes, digital compact cassettes (dcc) and diskettes.
caring for electronic media 