How to Demagnetize an Object
A magnet is a material that produces a magnetic field through alignment of magnetic domains. Magnetic domains are tiny regions in the material that behave like magnets. Each domain has a north and south magnetic pole. In magnetised materials, the poles of these domains align so they all point in the same direction.
As a result, the magnetic fields of the domains support each other to produce a significant magnetic field or strong magnetic material. To demagnetise the material, the alignment of these domains must be interrupted so that the domain fields cancel each other.
Fold the towel twice to produce a soft cushion. The towel will protect your work surface and will provide some surface protection for the magnetised metal object during demagnetisation.
Test for the presence of a magnetic field in the object using a compass. The south of the compass needle will align with the object's magnetic north pole. Rotate your object. The compass needle will follow the movement of a magnetised object.
Place the magnetised metal object in the centre of the folded towel. Position the object so that the long axis of the object is not aligned with the north-south poles of the earth. To find the north-south poles of the earth, move a few meters away from the magnetised object before using your compass. Away from the magnetised object, the compass needle will align with the earth's magnetic field.
Use the hammer to strike the metallic regions of the magnetised object. Take care to avoid any parts of the object that may contain ceramic or which appear fragile. Strike the object a minimum of 20 times with light to moderate force. It is not necessary to use excessive force that may damage the object. The jarring caused by striking the object with the hammer will result in misalignment of the magnetic domains.
Repeat the test for the presence of a magnetic field described in Step 2 to determine if the demagnetisation procedure was successful. If the compass needle aligns with the magnetic field of the object and follows the movement of the object, the object is still magnetised. Repeat step 4 until the compass needle does not appear to be influenced by a magnetic field associated with the object. The object is demagnetised when it no longer influences the direction of the compass needle.