I now have a pretty strong magnet for magnet fishing, the problem that I am running into when taking it places is that I need away to isolate it from my wallet/phone/compass inside my backpack as otherwise they could be damaged.

My current solution is to roll it up inside several socks, is there a better way of doing this?

  • Contain it within some type of magnetic material (e.g., steel). Stronger the field the thicker the material needs to be. – topshot Dec 6 '18 at 22:01
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    @topshot Next question, how do I get my powerful magnet out of its steel container? – Reinstate Monica Dec 6 '18 at 22:03
  • My solution would be to keep my phone and wallet in my pocket. Or maybe hold the magnet in my hand. – Monster Dec 7 '18 at 6:37
  • Pry bar? :P Perhaps pad the container with foam so it's not in direct contact. I'm not so sure about the answer saying there's nothing to worry about. It would certainly wipe out the card strips if close enough and interfere with the reception of the phone. I've not studied (I'm an EE but from long ago) how such a strong magnetic field would (if at all) interfere with flash memory or RFID since those didn't exist at the time and I've been in software dev since school. – topshot Dec 7 '18 at 12:25
  • flash memory: superuser.com/a/338656 – topshot Dec 7 '18 at 13:08

Physically speaking, you cannot shield magnetic fields -- you can just "dilute" them.

Lets set the discussion aside for this answer, whether a permanent magnet can be strong enough to damage electronics. To prevent magnetic field strength from being to high at the place of magnet sensible stuff you have two possibilities:

  1. Put distance between the magnet and the things to be protected. Your approach with packing the magnet into some socks is exactly that.
  2. According to this page you can reduce the magnetic field strength by putting it behind an iron plate or into an iron container to separate it from the sensible stuff. This will dilute the magnetic field lines more effectively than just putting spatial separation between them.

However, at least with the iron container, you will of course have the problem of getting the magnet out of the container. If you take the iron plate approach, you might put the magnet close to your backpack's outer wall and use the plate as a separator towards the rest of the pack's content.


There is no magnet you can lift that is strong enough to damage a cell phone, so don't worry about your phone, apart from physicial damage e.g. dropping it on your phone. You may need to be careful the phone doesn't violently thrash into the magnet, but other than that, electrically phones are virtually unaffected by magnetism.

As for your wallet, chip cards are also not affected, so just rely on those and a little cash.

In other words, you really don't need to do anything.

  • Sources for your claims? – topshot Dec 7 '18 at 12:25
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    This might NOT be true. Small Neodymium magnet can totally destroy some monitors. "Someone" placed a half-dollar sized Neodymium magnet on the outside of my closed laptop computer. When I opened the thing up I found that the screen was messed up - parts were unresponsive, other parts had white or black bands, and then there were mixes of colors. I eventually had to replace the screen because the device was unusable. – That Idiot Dec 7 '18 at 13:43
  • @topshot - there are several cell phone holders (for car dashes, etc.) that use a fairly strong magnet mounted on the phone case to hold the phone onto a ball or flat support. So it isn’t totally out of the question. Still, a wooden box might be a reasonable answer to the OP... – Jon Custer Jan 6 at 17:51
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    This is arguably false for cell phones, but it is demonstrably false for thins such as credit cards etc. that come with magnet strips. Just try it out and swipe any of your magnet strip cards with a small fridge magnet... (actually, don't do that!) – fgysin reinstate Monica Jan 7 at 9:31
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    Also available portable neodymium magnets have reached ridiculous strengths, with some of the strongest ones being able to hold several hundreds of kilograms if attached to a suitable metal surface. The sheer force is likely enough to mess up whatever you attach to such a magnet... – fgysin reinstate Monica Jan 7 at 9:32

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