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 tape head cleaner, erasing hard drives, degaussing equipment, and degaussing services, see also: rsa data security inc. hard drive cleaning software erase a hard drive permanently erase data hard drive homemade degausing coil delete files from hard drive mbi degaus clean hard disk thompson financial security data degausing coil construction clean hard drives hard drive erase program erase free space on hard drive media cleaner profiles download degaussing facilities erase index.dat files wipe out a hard drive format hard drive erase government data clean clean a hard drive clean install of windows instructions format hard drive thompson financial security data destroy data and hard drive hard disk cleaners how to erase a cd r deep clean hard drive clean hard drive reinstall windows 98 hard drive cleaning tips how to erase hard drive in dos data link layer security software to clean up hard drive offshore data security how to degauss your television hard disk clean up software free erase free space on hard drive maryland state data security erase internet files delete partitions on hard drive erase hard disk mac keyboard command degausing a tv homemade degausing coil

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 tape head cleaner, degaussers, erasing hard drives, cleaning hard drives, degaussing, and erasing harddrives, see also: