Not all degaussers are created equal

If you’re reading this, you’ve probably heard a thing or two about degaussers. You’ve heard they’re the best way to remove data from old hard drives before disposing of them. You may have heard that NIST, the group which maintains international standards for data security, recommends the use of a degausser before any other method of destruction. But have you heard that not all degaussers are created equal?

Take a look around online and you’ll find a variety of degaussers from a range of manufacturers. Some of these models may seem cheap and cheerful. “A perfect budget degausser for me,” you might think – but be warned, the devil’s in the details. There are two major differences in features to be aware of. The first, of course, is the degausser’s power – or Gauss level. The Gauss level determines what manner of hard drives and other magnetic media the degausser is actually capable of erasing. A recommended minimum level for erasure of modern hard drives is 10,000 Gauss – also known as 1 Tesla. Any less Gauss than this, and you’ll need to make multiple passes over the media to ensure it’s completely wiped. This brings us neatly to our second point.

Degaussers come in two varieties – “continuous duty”, and “non-continuous”. Continuous duty refers to the ability to run the degausser, well, continuously – without needing to wait for it to cool down between uses. Any good-quality degausser built within the last decade will be continuous duty. Unfortunately, many retailers continue to sell non-continuous models, typically of the “flatbed” variety – and some manufacturers continue to produce them. There are a few things you need to know about flatbed degaussers: they’re slow, they’re unreliable, and they’re downright unsafe.

A flatbed degausser resembles a flatbed scanner. (The clue’s in the name really.) Place the hard drive to be erased onto the degausser surface, and run the machine. But unlike a scanner, the process isn’t that simple. The electromagnetic field created by one of these machines is uneven, requiring the user to move and rotate the hard drive around on the surface to ensure it is properly erased. This field is also uncontained, constituting a real safety risk. Imagine a miniature MRI machine, and you’re not far off. The biggest danger to the user is heat output; flatbed degaussers generate a *lot* of heat, such that the machine must be given time to cool down between operations, and the user should wear protective gloves when handling drives.