🚀 go-pugleaf

In article <1hsqkaINNlrs@agate.berkeley.edu>, andywang@crown.berkeley.edu (Andrew Wang) writes:
> charltn@ccu.umanitoba.ca (Jim Charlton) writes:
> 
>>In <1992Dec30.000429.24047@panix.com> schuster@panix.com (Michael Schuster) writes:
> 
>>>I'd often wondered about the magnetic safety of mailing diskettes.
>>>Wondered how many diskettes that arrived unreadable were really
>>>due to exposure to magnetic fields during transit.
> 
>>>Today in my mailbox was a post card from Pizza Hut. Taped to it was
>>>a magnetic sticker, suitable for posting on your refrigerator door,
>>>with the phone number of my local store.
> 
>>>Good thing no software publisher was mass-mailing update diskettes
>>>this week, eh?
> 
>>I also wondered how susceptible disks were to magnetic fields.  So I
>>took a disk, half filled with files, and exposed it to the field of a
>>strong horseshoe magnet (3 1/2" diskette).  While I could easily pick
>>the disk up by its metal gate I could not in any way corrupt the data
>>on the disk!  I suspect that data is much less vulnerable to static
>>magnetic fields than is commonly thought.  Alternating current
>>electromagnets/transformers etc. may be much more damaging but I conducted
>>no tests with alternating fields.
>>   jim...
>>charltn@ccu.umanitoba.ca
> 
> I took a bunch of old 360k floppies and put them in the middle of
> a 12" monitor degaussing coil. After 10 seconds of degaussing, I tried
> three of the diskettes and could still read their directories no problem.
> I didn't try to read any files, though.
> 
> Andrew

I have successfully erased beyond recognition 5 1/4" and 3 1/2" disks using
a 40oz. magnet from the back of a 12" woofer, so it is possible.  The trick is
to sufficiently scramble the magnetic elements on the disk by moving it around
close to the magnetic source (magnet).