When you re-record only the particles that make up the new signals are re-arranged. This leaves some particles in the original orientation, which causes spurious signals.
This can cause bad sound and picture quality on broadcast tapes and read and re-write errors on data tapes.

Why can't I run the media through my recorder using the erase button?
Erasing on a recorder ties up an expensive piece of equipment for maybe hours and puts unnecessary wear on the heads and drive mechanism. A degausser will give a deeper, more even erasure in seconds.

Why shouldn't I re-format my media on my computer?
Formatting can take many minutes; making the computer in operative and putting unnecessary wear on an expensive piece of equipment. When re-formatting media it is possible for tracks to be missed, this could cause read and re-write errors. A degausser will completely clear your media of all data in seconds.

What makes a degausser erasure so good?
In the manufacture of magnetic media one of the last production processes is for all magnetic media to be degaussed. This ensures that all the particles are orientated completely at random leaving the media free of any spurious signals.By degaussing magnetic media before re-using you are returning it to its original condition with all the particles orientated at random.

What are the benefits?
1: For the radio and television broadcast industry expensive media can be re-used many times, making cost effective savings.
2: For the computer industry, storage media can be used many times without read or re-write errors.
3: For security old storage media can be thrown away completely free of any sensitive information.
4: Magnetic media duplicators can re-cycle over runs and returns

What sort of erasure levels can I expect to get?
Using tape industry standard test:
-90dB on magnetic media up to 750 Oe
-75dB on magnetic media up to 1500 Oe

What type of degausser do I want?
The type of degausser needed is very much dependent on three main factors:

1. The type of magnetic media being used.
2. The amount of media to be erased in a given period.
3. Are they a single or multi type media user?

Magnetic media comes in many different energy values and types. But as far as degaussers are concerned we can narrow this down to two types.

1. Oxide based media with an oersted value up to 750 Oersted (Oe)
2. Metal based media with an oersted value up to 1500 Oersted (Oe)

Here we have four basic types:

1. Manual or automatic with limited duty cycle for media up to 750 Oe.
2. Automatic with continuous duty cycle for media up to 750 Oe.
3. Manual or automatic with limited duty cycle for media up to 1500 Oe.
4. Automatic with continuous duty cycle for media up to 1500 Oe.