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 what will happen if i erase my hard drive, erasing hard drives, degaussing equipment, and degaussing services, see also: how to delete hard drive how to clean out hard drive on computer how to delete unused data in ms systems config how to wipe your hard drive honeywell media air cleaner delete from data adapter video tape eraser wipe out a hard drive hard disk cleaners will mother board failure erase data on hard disk deep clean hard drive permanently delete files from hard drive thurough hard drive cleaning lost data in windows security event log hard disk clean up software delete your hard drive pc hard disk cleaner expo dry erase cleaner material safety data sheet ships degaussing principle v91m hd hard disk drive degausser why can't i erase data off my cd-rw disc completely wipe hard drive how to wipe hard drive erase unix hard drive data mbi degaus secure erase for new install more data less security politician wipes hard drive wipe the hard drive delete hard drive to reinstall windows 98se how do i erase a hard drive wipe hard drive with cipher.exe data warehouse control and security totally erasing a hard drive degauss video m100 erase all data erase free space on hard drive how to erase hard drive in dos ptc degaussing cleaning up hard drive

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 what will happen if i erase my hard drive, degaussers, erasing hard drives, cleaning hard drives, degaussing, and erasing harddrives, see also: