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 offshore data security, erasing hard drives, degaussing equipment, and degaussing services, see also: erase files in the restore directory security data guard technology erase hard drive on mac computer virus erases data on hard drive offshore data security how to clean a hard drive completely wipe hard drive free computer virus erases data on hard drive software to clean up hard drive secure erase hard drive erase index.dat files thompson financial security data how to wipeout a hard drive v91m hd hard disk drive degausser clean and re format hard drive degausing coil construction degauss thermistor tape cleaner delete your hard drive hard disk cleaners how to delete unused data in ms systems config computer virus erases data on hard drive erase access denied files erase files in the restore directory how do i erase a hard drive thurough hard drive cleaning sdlt tape eraser erase aol cd erase all data palm grid data security mds-4 degausser & prices how do i erase a hard drive grid data security degauss equipment compact disk data security data link layer security does formatting hard drive erase data completely disc cleaner dss files erase clean hard disk

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 offshore data security, degaussers, erasing hard drives, cleaning hard drives, degaussing, and erasing harddrives, see also: