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How to Demagnetize Iron

Iron and other ferrous metals are easily magnetized. Sometimes this happens accidentally, and other times it's done deliberately for practical reasons or as a schoolroom demonstration. Inadvertently magnetized metal can interfere with sensitive electronics and data storage media, and can distort the image on your computer monitor. If you find yourself needing to demagnetize a piece of iron, there are three simple and practical ways to go about it. One uses a magnet, a second uses physical force and a third uses heat.

Things You'll Need

String
Small, powerful magnet
Iron filings or magnetic compass
Hammer
Baking sheet
Oven
Outdoor barbecue (optional)

Instructions

Magnet Method
- 1
  Hang the magnetized piece of iron from a string and wait for it to stop spinning. It will orient itself north-south, like the needle of a compass.
- 2
  Place the south pole of the magnetized item on a small, powerful magnet.
- 3
  Slide the length of the iron along the magnet, or slide the magnet along the length of the piece of iron, whichever is more convenient.
- 4
  Continue to stroke the piece of iron from its south pole to its north pole, until you have neutralized its original magnetism. Check the remaining magnetism periodically by holding the piece of magnetized iron over iron filings or a magnetic compass. When it no longer causes any movement, it's effectively demagnetized.
Shock Method
- 5
  Take your piece of magnetized iron and drop it several times on a hard surface, or strike it repeatedly with a hammer.
- 6
  Test the level of remaining magnetism by holding it near iron filings or a magnetic compass.
- 7
  Repeat the jarring blows until your piece of iron has lost its magnetism.
Heat Method
- 8
  Set your piece of iron on a baking sheet and place it into a preheated oven at 475 degrees F. If the iron is too large to conveniently fit in the oven, an outdoor barbecue is a suitable alternative.
- 9
  Raise the temperature of the iron to 460 degrees F. This is the point at which it loses its magnetism, also referred to as the "Curie point."
- 10
  Cool the iron until it can be handled comfortably. Test it by holding it near some iron filings or a magnetic compass. If it still retains some magnetism, repeat the process, but leave the iron in the hot oven for an extra 10 to 15 minutes.

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