Can a Magnet Erase a Floppy Disk? Rethinking the Rules of Preservation
Can magnets erase floppy disks? Research presented at iPRES 2026 examines magnetic damage, USB drives, and the challenge of preserving obsolete media.
Keep magnets away from floppy disks. That used to be a simple rule.
Digital preservation researcher Ross Spencer decided to test it. He left a magnet resting on a floppy disk for three weeks, checking the data’s checksums each day.
Nothing changed.
In September 2026, Spencer and three colleagues presented Myths, Risks, and Realities of Floppy Disk Preservation at iPRES, the international conference on digital preservation.
The research draws on the work of Tyler Thorsted, Leontien Talboom, Julianna Barrera-Gomez, and Spencer. It examines familiar advice about reading, handling, cleaning, and storing floppy disks.
The point wasn’t to prove that conventional advice was wrong. It was to find out which warnings are supported by evidence, and how they apply to the disks that archives are actually trying to read.
What Does a Magnet Actually Do?
Spencer described his experiment in a blog post published on October 11, 2026.
He kept a magnet in the same position on top of a disk for three weeks and monitored the checksums. Under those conditions, he detected no change.
That doesn’t mean magnetic fields are harmless.
A 1993 study published in Radiology exposed high-density 3.5-inch floppy disks to magnetic fields. The researchers reported no data loss at field strengths up to 500 gauss, while exposure to 1,000 gauss erased the recorded data in their experiment.
Field strength, distance, and exposure conditions matter. Spencer’s result only describes the particular setup he tested. It does not establish that a stationary magnet is safe in general.
An old precaution can be sensible without accurately describing every situation. The useful question is what the actual risk is, and when it becomes significant.
Do We Really Need Specialist Equipment?
Preservation specialists often use controllers such as Greaseweazle and KryoFlux.
They can capture magnetic flux transitions from a disk, making it possible to investigate unusual formats or interpret a recorded stream again without repeatedly reading the physical medium.
These tools are especially valuable for archives dealing with a wide variety of old disks.
But Spencer argues that ordinary USB floppy drives still have a role.
For a small collection of standard 3.5-inch disks, a USB drive may be enough to produce a usable disk image. It can provide a practical starting point without the cost and complexity of a specialist setup.
There are limits. USB drives cannot generally capture flux-level data, may not support nonstandard formats, and require precautions against unintended writes.
In another example discussed by Spencer, researchers recovered additional data from a disk severely damaged by magnetism when they increased the number of ddrescue reading passes from two to five.
More attempts do not guarantee recovery. A physically damaged disk can deteriorate further when repeatedly spun in a drive.
The point is to choose equipment according to the condition of the medium and the information that needs to be preserved—not simply to use the most sophisticated tool available.
The Knowledge Is Disappearing Too
Behind the research is a larger issue: much of the practical knowledge needed to read old disks is becoming harder to find.
Different computers used different recording formats. Drives may need servicing. A disk can look perfectly ordinary while containing data that a modern USB drive cannot interpret.
Cambridge University Library’s Future Nostalgia project is working to document this knowledge alongside the media itself.
In November 2025, the project published Copy That Floppy!, a free guide covering media identification, hardware selection, cleaning, and disk imaging.
It draws on expertise from the retrocomputing community as well as institutional preservation specialists.
That matters. Some of the people who best understand obsolete hardware are those who have continued repairing and using it long after manufacturers stopped supporting it.
Keeping a drive is useful. Knowing how to use it, and how to interpret what it reads, is just as important.
From a Floppy Disk to a Photograph
At Still Memoir, this is more than a historical question.
Our ongoing series Residual Blue uses a Sony Mavica, an early digital camera that records images onto 3.5-inch floppy disks.
The low resolution, limited storage, and slow recording process are part of how the photographs are made.
But using a floppy disk to produce a photograph is different from relying on that disk to preserve it.
Once a photograph has been recorded, the files can be copied to contemporary storage, checked, and backed up. Where appropriate, a complete disk image can be retained as well.
The original disk can remain part of the work without being its only surviving copy.
Japan’s National Diet Library highlighted a similar problem in a 2023 report: preserving digital records depends not only on the condition of the media but also on continued access to compatible reading equipment.
A twenty-year-old floppy disk may still read perfectly today. That says little about whether the same will be true in another decade.
While the Disks Still Work
The iPRES research does not prove that floppy disks are more durable than previously believed.
It asks preservation practitioners to test inherited assumptions against practical evidence.
Some disks need specialist equipment. Others may be readable with an ordinary USB drive. Magnetic risk depends on the circumstances.
And there is a more uncomfortable lesson in the amount of effort now required to recover old media: much of this data could have been migrated when the drives were still common.
We don’t need to find out how long a floppy disk will last before moving its contents somewhere safer.
We can do that while it still works.
References
- Tyler Thorsted, Leontien Talboom, Julianna Barrera-Gomez, Ross Spencer, Myths, Risks, and Realities of Floppy Disk Preservation (2026)
- Ross Spencer, Just one more thing: Myths, Risks and Realities of Floppy Disk Preservation (2026-10-11)
- Future Nostalgia Project, Copy That Floppy! (2025-11-21)
- J. E. Gray and J. P. Taubel, Effects of ionizing radiation and magnetic fields on digital data stored on floppy disks (1993)
- National Diet Library of Japan, Report on Long-Term Preservation Measures for Floppy Disks (2023, Japanese)
