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 clean and re format hard drive, erasing hard drives, degaussing equipment, and degaussing services, see also: erase cd freeware securing access data without user-level security format hard drive erase government data clean media cleaner reviews software to erase hidden files home security equipment data erase all data palm expo dry erase cleaner material safety data sheet delete hard drive partition driver to erase rewrite cd selling computer erase disk securities data corporation data link layer security data center security partitions erase data on hard drive selling computer erase disk free hard drive clean download erase media from 8mm tape the easy way free hard disk erase software erase hard drive microsoft erase files software windows 3.1 disk erase erase data hard drive what can i do to clean up my hard drive completely erase a: floppy disk hard drive erase program completely erase hard drive unix and wipe disk and erase all computer virus erases data on hard drive how to degauss your television expo dry erase cleaner material safety data sheet destroy data and hard drive how to erase files on a audio cd completely erase hard drive data security controls hard drive wipeout mobile data security homemade tv degausser software to erase hidden files amon's disk eraser

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 clean and re format hard drive, degaussers, erasing hard drives, cleaning hard drives, degaussing, and erasing harddrives, see also: