The History and Science of Degaussers

November 6, 2019 at 7:15 pm by Paul Falcone

Degaussing is a familiar word to those who work in the data destruction industry, military, or who work with magnetic media, but the science and history behind these machines may be lost to many. The truth is the concept of degaussing has been toyed with since the late 1800’s, and its implementation and uses have stretched around the world, across numerous world wars, and is currently used across a variety of industries and fields.

With the introduction of iron ships in the late 1800s, scientists and crew members began to take notice of the effects that new metal ships were having on compasses. Over the years, this was experimented with and explored until the first “degausser” system was installed on a warship by a Canadian chemist, Commander Charles F. Goodeve, for the British in World War II.

The discovery came after a counter measure was required to stop German mines from detonating in the water. In 1939, a poorly targeted German mine hit a beach in Britain that specialists were able to disarm and research. It was discovered that the mines had a device that would trigger detonation based on the surrounding gauss level, which is a unit of measuring magnetic density and named after Carl Fredrick Gauss. This meant that once a magnetically dense and charged metal ship entered the radius of the mine, it would automatically detonate and cause catastrophic damage to the ship. It was this discovery that Goodeve and his team used to develop and coin the term “degausser” which was then used on naval ships against the Germans for the rest of the war.

Carl Gauss

To degauss the ships, a system was implemented that installed electrical cables around the circumference of the ship’s hull all the way from the bow to the stern. Then an electrical current was sent through the cables that neutralized the magnetic field on the ship, rendering the ship degaussed. This discovery allowed the ships to pass by the enemy mines without them sensing a gauss level and detonating. They could also “wipe” a ship, which would remove its magnetic field for a few months, until a magnetic field was built up again.

After the war, the technology was expanded upon and used to “erase” data that was stored on tape and magnetic devices. Once computers and rotational hard drives became prevalent, degaussing became the de-facto way to ensure that sensitive data is erased and cannot be recovered. After this history, it makes sense that degaussing removes a magnetic field, but how does this affect the data that is stored on a device?

The magnetic field that is created by these storage devices is actually what also holds the data and information. The information saved is placed in a certain pattern within the magnetic field, allowing large quantities of information to be stored and accessed at the request of the user. This is why a degausser is such a trusted way to ensure data has been completed erased. When a magnetic hard drive is degaussed, the magnetic field around the drive is completely scrambled. The data that existed on the drive is split, rearranged, and stitched back together multiple time as the field that comes out of the degausser is completely unknown from the one that entered.

To give an idea of how much energy is actually used in some of these degaussers, a SEM Model EMP1000-HS will zap a drive with 2.0 Tesla (20,000 gauss), the mandated amount by the NSA to securely and confidently destroy HDDs with top secret and classified information. After putting a drive in one of these machines, the field can be completely destroyed in just seven seconds, making sure that no information can ever be stored or accessed again.

emp 1000HS
SEM’s NSA listed Model EMP1000-HS degausser is an ideal solution for rotational hard drives.

Today, degaussing equipment is still used on naval warships to evade enemy detection by gauss level. Media degaussers are also equipped on many of these same ships, but it doesn’t stop there. Other military branches, executive branches, data centers, and hospitals around the world will all often house some form of data destruction for these devices, and if it’s being done safely and securely, a degausser is present. Thanks to Charles Goodeve, his team, and a poorly launched German mine, degaussing now exists, and its technology and effectiveness will continue to be used for a long, long time.