What are magnets coated with?

2nd March 2020


	What are magnets coated with?


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			Magnets need to be coated or they will corrode quickly when left exposed to the elements. All magnets, except for weld clamp magnets, magnetic sweepers, hand magnets, and magnetic mounting pads can be coated in a large range of different materials. The most common coatings are listed below:

			Nickel-copper-nickel
			Nickel-copper-nickel coatings, (known as nickel coatings), consist of three different coats: nickel, a layer of copper, and then a second layer of nickel.

			This type of coating can be painted over, which makes a nickel-copper-nickel coating more visually attractive than the other magnetic coatings available.

			This method of painting the coating is used on bar magnets which need the different magnetic poles to be painted in different colours for educational purposes.

			Epoxy
			Epoxy is a type of plastic coating that improves the corrosion resistance of a magnet. This type of coating will last a long time if it is not damaged in any way, however it is easily scratched which makes it one of the least durable coatings for a magnet.

			Zinc
			Magnetic discs, bar magnets and horseshoe magnets can all be coated in zinc, which provides the magnets with corrosion resistance as well as being relatively cheap to use.

			The zinc coating works as a sacrificial coat for the magnet – this means that the layer of zinc will wear off before allowing the magnet to corrode. Zinc is a natural water barrier, therefore if no water can get to the magnet then there will be no corrosion.

			Polytetrafluoroethylene (PTFE)
			Polytetrafluoroethylene (PTFE), also known as teflon coating, is another form of protection given to magnets. PTFE coatings are used to improve the impact resistance and allow two magnets to slide apart easily when they have been attached.

			PTFE coating is particularly useful for classroom demonstrations on how magnets work, as the coating protects the magnets from breaking, which is a particular hazard when children are playing with them.

			Gold
			Magnetic discs can be coated in 22 carat (K) gold. Magnets with this coating are used in magnet therapy where it is believed that magnets help to cure many different ailments.

			The gold coating is used to help protect the user’s skin from the materials, (e.g. neodymium) which are used to make the magnet. The materials in a magnet can cause the skin to become irritated if they are in contact with it for a long period of time.

			Which coating should you choose?
			Which coating you choose will depend largely on the level of corrosion resistance you require as this is the coating’s main role. The coating that provides the highest level of corrosion resistance is zinc. It is also relatively affordable in comparison to the other coatings, making it an economical coating to choose.