A degausser is a device used to erase magnetic media through the use of a magnetic field. Degaussing renders data on magnetic storage devices such as hard disk drives, diskettes, reel-to-reel tapes, and other magnetic tapes inaccessible by randomizing the magnetic domains on the media.
What is degaussing?
Degaussing is the process of applying an alternating magnetic field to magnetic storage media to disrupt the recorded magnetic domains. This renders any previously stored data on the media inaccessible. The magnetic field applied by a degausser randomizes the orientation of the magnetic domains on the media.
Degaussing was originally developed to reduce the magnetic signature of naval ships to avoid detection by magnetically triggered sea mines. The process was later adapted to enable the erasure of data from magnetic storage media.
Degaussers work by exposing the target media to an alternating magnetic field that gradually decreases in intensity. This effectively magnetizes the media in one direction, then reverses the magnetization in the opposite direction. As the magnetic field strength decreases, the magnetic domains stabilize in random patterns, erasing any previously stored data.
Why degauss magnetic media?
There are several reasons organizations may want to degauss magnetic media:
- Erase sensitive information – Degaussing is an effective way to permanently erase confidential or sensitive data from magnetic media before disposal or repurposing.
- Prevent data recovery – Even deleted files can potentially be recovered from magnetic media. Degaussing makes data virtually unrecoverable by randomizing the magnetic domains.
- Comply with regulations – Some industry standards and government regulations require the sanitization of data from magnetic media before disposal. Degaussing helps meet these compliance requirements.
- Reuse media – Degaussed media can be reused while retaining the original media format and integrity.
- Reliability – Degaussing is generally more reliable than simply deleting files or reformatting magnetic media to erase data.
Degaussing effectively sanitizes magnetic media to a high standard while enabling media reuse. This makes it a preferred method for rendering data unrecoverable before media disposal or repurposing.
Types of magnetic media that can be degaussed
A variety of magnetic media can be erased through degaussing. Common media types include:
- Hard disk drives (HDDs) – HDDs used in computers, servers and storage systems store data on rapidly rotating magnetic platters. HDDs are readily erased by magnetic degaussers.
- Diskettes – Floppy diskettes (disks) encoded data on a thin, flexible magnetic foil. Diskettes are easily degaussed even using simple wand-style degaussers.
- Magnetic tapes – Tape media includes reel-to-reel, cassette tapes, video tapes and more. Magnetic tape degaussers can sanitize entire tape reels in seconds.
- Data cassettes – OBSOLETE – Cassettes that contain magnetic tape reels or disks can be degaussed, but require dismantling first.
- Credit cards – Credit cards have a magnetic stripe that can be degaussed to erase account data. Wand degaussers are typically used.
- Audio cassette and VHS tapes – Cassette tapes store analog audio and video signals magnetically. Standard media degaussers can erase their contents.
In general, any magnetic media that stores data by magnetizing a magnetic medium can be erased by degaussing. This includes hard drives, floppy disks, and magnetic tapes from audio cassettes to large computer tape reels.
What types of degaussers are available?
There are a few common types of degaussers suitable for different media types and degaussing needs:
- Coil degaussers – These consist of a large coil of wire through which a strong alternating current is passed to produce a fluctuating magnetic field. Hard drives and diskettes can be simply passed through the coil for degaussing.
- Wand degaussers – Small handheld wands containing an electromagnetic coil. The coil is manually brought near media like credit cards or diskettes to degauss them.
- Tunnel degaussers – Media on reels or cassettes is transported through a long tunnel degausser on a conveyor. The tunnel exposes media to a comprehensive alternating field.
- Tabletop/hand crank degaussers – Compact degaussers with a powered internal coil. Media is manually inserted for degaussing. Some feature a crank to move media past the coil.
- Free fall degaussers – Large chambers where media physically falls through a strong alternating electromagnetic field for degaussing.
The optimal degausser type depends on the media quantities and form factors to be erased. For example, wand degaussers suit small volumes of magnetic cards and diskettes. Free fall degaussers efficiently handle bulk erasure of tapes. Tunnel degaussers accommodate both.
Degaussing magnetic media – step by step
Degaussing magnetic media like hard drives is a quick process when using the right degaussing equipment. Here is a typical workflow:
- Select a degausser matched to your media type and volumes. For HDDs, a coil or tunnel degausser is suitable.
- Secure any loose internal components in HDDs. This prevents damage during degaussing.
- Power on the degausser unit and allow it to stabilize. This produces the alternating magnetic field.
- Pass HDDs through the degausser coil or tunnel. For wand degaussers, slowly wave the wand over the media. Go through the motions a few times to ensure full degaussing.
- Run a sampling of media through a data recovery service to verify successful sanitization.
- Reuse or responsibly recycle the degaussed media.
Going through this process with adequate degaussing field exposure erases even residual data remnants. It provides quick, convenient, and reliable media sanitization.
Factors affecting degaussing effectiveness
To reliably sanitize magnetic media through degaussing, it helps to be aware of factors that influence effectiveness:
- Magnetic field strength – The field must be strong enough to penetrate the media material and randomize magnetic domains. Handheld degaussers tend to be less powerful.
- Field direction – Multidirectional fields that reverse are more effective than static unidirectional fields.
- Duration of exposure – The media should be exposed to the fluctuating field for a sufficient duration – at least several seconds to a minute depending on the field strength.
- Media composition – Denser platters and casing materials can inhibit field penetration. Composite media is more resistant to degaussing.
- Media movement – Moving media through a continuously reversing field boosts degaussing. The motion should not be too quick.
- Number of passes – Passing media through the field two or more times improves degaussing efficacy.
Optimizing these parameters allows magnetic media to be reliably erased. Tunnel and free fall degaussers automatically account for most of these factors.
Limitations of degaussing
While an effective sanitization technique, degaussing does have some limitations:
- It permanently erases all data – degaussing is not selective. The entire media is erased.
- Electronics can be damaged – HDD internal components may be damaged if not properly secured.
- Not effective for flash media – Flash memory is not magnetic and can’t be degaussed. Other techniques like encryption are required.
- High security applications – Degaussing may not meet erasure standards for highest security applications like financial data.
- Verification – The process does not inherently verify erasure. Random checking of degaussed media using data recovery tools should be done.
For these reasons, degaussing may not suit every media sanitization need. Proper precautions are still required to avoid data leakage from degaussed media.
Security of degaussed media
When implemented correctly using adequate field strengths, degaussing provides strong assurance of data being rendered unrecoverable. Some key security considerations include:
- Use high-field strength degaussers rated at a minimum of 10000 Oe (Oersted) field strength.
- Use tunnel/conveyor degaussers for reliable automated degaussing.
- Degauss HDDs with platters and heads removed or securely locked down.
- Perform multiple field reversals and transits through the degausser.
- Sample check erased media using forensic data recovery tools.
- Destroy media platters after degaussing for highest security when disposing hard drives.
With the right techniques, degaussing can sanitize magnetic media to an extremely high standard exceeding even military grade erase requirements.
Conclusion
Degaussing provides a fast, convenient and reliable method to sanitize magnetic storage media. A wide range of magnetic media can be erased, from hard drives and tapes to floppy disks. Both manual and automated degaussers are available to suit different sanitize needs. While degaussing effectiveness depends on magnetic field strength and direction, degaussing remains a go-to technology for rendering data unrecoverable from magnetic media.