An alternating current (AC) bulk eraser (degausser) is used for complete erasure of data and other signals on magnetic media. Degaussing is a process where magnetic media is exposed to a powerful, alternating magnetic field. Degaussing removes any previously written data, leaving the media in a magnetically randomized (blank) state.

The degausser must subject the media to an alternating magnetic field of sufficient intensity to saturate the media and then by slowly withdrawing or reducing the field, the magnetic media is left in a magnetically neutral state.

To erase recorded data, it is necessary for the strength of the degaussing field to be greater in value than the coercivity of the magnetic media. Simply stated, coercivity is the magnetic field strength, rated in oersteds (Oe), required to change the magnetic orientation of the magnetic material. Check with knowledgeable dealers or degausser manufacturers to identify degausser models that meet your requirements.

Data is typically not lost until its level has been decreased 65% to 75% (or more) below its original saturation recording signal level, dependent upon the drive system.

 

For more information on compact disk data security, erasing hard drives, degaussing equipment, and degaussing services, see also: degauss coil wand lost data in windows security event log secure erase for new install compact disk data security data warehouse control and security free hard drive clean download video tape eraser how to erase hard drive in dos permanently delete files from hard drive delete hard drive to reinstall windows 98se recuperate erase files wipe the hard drive erase cd-r erase files in the restore directory how do i completely erase a hard drive data security policies definition of data cleaning mds-4 degausser & prices free hard drive clean download secure erase hard drive clean hard disk how to erase a cd unix tool erase disk rsa data security inc. ships degaussing principle hard drive cleaning software hard disk cleaners unix and wipe disk and erase all best media cleaner settings delete from data adapter rsa data security completely erase a: floppy disk why can't i erase data off my cd-rw disc completely erase a: floppy disk degausing coil construction clean hard drives erase aol cd erase a hard drive steps clean hard drive xp erase hard disk mac keyboard command

A complete erasure level, for most users, is considered to be 60 dB below the original signal level – this of course depends on user requirements. A 60 dB signal decrease equates to reducing the signal to one tenth of one percent of its original value.

Magnetic media products that have factory prerecorded magnetic servo patterns should not be degaussed. Degaussing would erase the factory written magnetic servo signals and leave the media unusable. For all other magnetic media (without magnetic servo signals), after proper degaussing, the quality of subsequent data recording should be unchanged or even improved.

It is very important to understand and follow the degausser’s operating instructions. This is especially important for manual units where the operator controls the media’s movement through the degaussing field. For higher coercivity media, four passes are often recommended – two passes, with a 90 degree rotation for the second pass, and then repeat the process with the media turned upside-down. Of course, these and other important operating considerations will vary with the type, power and construction of the individual degausser models.

For more information on compact disk data security, degaussers, erasing hard drives, cleaning hard drives, degaussing, and erasing harddrives, see also: