How To Demagnetize a Magnet - Complete How-To Guide

Throughout frequent use and occasional mis-haps, it is possible for a magnet to lose some of its strength or just stop working completely. This can be inconvenient in some cases, but very convenient in others. Interested in this topic, I did some research to find out how magnets are generally de-magnetized.

How do you demagnetize a magnet? Magnets can be de-magnetized in several ways: from excessive heat exposure, high levels of shock or force, and improper storage, all the way to corrosion. In order to purposefully de-magnetize a magnet, you can apply any of these components to the magnet in question.

When it comes to using magnets on a daily basis, de-magnetization can seem like the end of the world. However, there might be a situation where you actually need your magnet to lose some strength.

Or, on the other hand, you might just be interested in the possibility of making a magnet lose its functions, and are looking for a fun science experiment. Either way, you will find all of the answers to your questions throughout the rest of this article.

How To Demagnetize a Magnet

A magnet can only truly be called a magnet if it continues to exert some kind of force. Regardless of the reason, there will come a time where a magnet will need to lose its magnetic properties.

This can be from accidents, like a small magnet being hit, broken or busted. This can also be intentional, like when an MRI magnet is “quenched” for safety or decommissioning, or when a magnet is hammered to dispose of it properly.

In any case, knowing how to demagnetize a magnet is a valuable skill in case of emergency, and knowing how to re-magnetize one is just as important.

Knowing the fundamentals of magnetism and the forces that govern it is key towards completing both processes.

Luckily, that is the very purpose of this article: to explain the basics behind magnetic fields, and especially how these basics can be applied to demagnetizing and re-magnetizing them.

By the end of this explanation, you should understand the fundamentals of magnetizing and demagnetizing a material, and hopefully apply these skills to your everyday life.

It’s possible, too; magnets are ubiquitous across our society - washing machines, planes, even our globe use the science of magnetism in their own ways, and we’re just going to scratch the surface of the topic, now.

Magnetism is still in the early stages of study, and this post will hopefully be a useful guide in navigating the exciting world of magnetic science.

To begin, we will answer the fundamental question of this entire article, which is how magnets are de-magnetized.

Here are some of the ways that magnets can be de-magnetized:

  • Excessive Heat
  • Shock (Force, Dropping, etc.)
  • Improper Storage
  • Corrosion

The four main ways that a magnet can lose its force include coming in contact with excessive heat, shock, improper storage, and corrosion.

While this is a list of problems that the average person would want to stay away from, you might be looking to try this out yourself. Whether you are searching with purpose or just for fun, take a look at the list down below to find out what you can do to de-magnetize a magnet.

How to De-Magnetize a Magnet:

  • Expose your magnet to high levels of heat
  • Throw the magnet on the ground
  • Hit the magnet with a hammer

As you can see, most of the methods for de-magnetizing a magnet come directly from the list of ways that magnets can use their strength naturally.

In order to do this intentionally, you can expose your magnet to high levels of heat, throw it on the ground, or hit it with a hammer.

If you complete these actions repeatedly and with enough force, you will be able to watch it lose its magnetic field right before your eyes.

However, if you plan on using your magnet again after this little experiment, you should be careful not to let it break into pieces of become deformed. This is something that can be irreversible, which we will get into throughout the rest of this article.

So, with all of that being said, can a magnet that has lost its strength ever be brought back to life, or re-magnetized?

The short answer to this question is: it depends. Seriously, it’s a difficult question to give a straight answer to without knowing what type of magnet you have, how strong it was to begin with, and if it’s even worth trying to save it.

Let me explain: there are multiple blockades towards re-magnetizing your materials, and it really does depend on the circumstance in which the magnetic field was lost.

Temporary magnets, for example, will always lose their magnetic field regardless of how well you take care of them, but they can be restored extremely easily.

There are not a lot of useful applications of temporary magnets besides entertainment, so I will not continue to mention them in this explanation.

To start, you do not need to be a physicist to experience magnetic fields firsthand; however, magnets losing their field can present serious problems to anyone unfortunate enough to witness their demagnetization.

But whether you are a nuclear physicist or a magnet fishing hobbyist, it is crucial to understand how magnets lose their magnetic field, and especially when it is worth it to attempt to revive a weakened magnet.

Thankfully, most magnets can regain their field if they’re basically untouched save for being exposed to a strong opposing polarizing force.

In other words, magnets that are repeatedly exposed to a force that repulses them can possibly be re-magnetized. However, they must still be physically intact, and come in contact with a strong magnetic field in order to begin the re-magnetization process.

Thus, there are a few circumstances where a magnet is a lost cause, which you will find in the table down below.

How Magnets Are Demagnetized:When Magnets Can’t Be Re-magnetized:
High heat Extremely high heat (for long periods of time)
Shock (force) Excessive force and breaking
Improper storage Deformities in shape
Corrosion Change in volume

Heat is the enemy of magnet integrity; not only can extreme heat weaken magnetic forces, it can disrupt the atomic makeup of the material and ruin your magnet, indefinitely.

With magnetism, a crystalline structure and like-facing electron polarities are key towards producing a net magnetic field -- when you expose this object to extreme heat, you change this meticulous structure and disrupt the underlying forces.

Electrons and their charges are delicate components, and while they can withstand all kinds of temperatures, extreme heat is very damaging.

Thankfully, the likelihood of a casual magnet user having access to the amount of heat needed to ruin a magnet is very low - magnet temperature is negligible until it reaches what is known as the Curie point.

The Curie point, or Curie temperature, is the minimum temperature a magnet can be heated to before it undergoes significant change that messes with its attractive and repulsive properties.

When a magnet is raised to the Curie temperature, it can only exhibit a weak force known as paramagnetic force from then on -- a weak attraction to a strong magnetic field.

Depending on how long the magnet was brought above its Curie point, it may be impossible to re-magnetize.

But like I said, it’s incredibly hard to heat a magnetic material past its Curie temperature.

The lowest Curie temperature for iron is 770 degrees Celsius, which is an insane amount of heat! You would essentially begin to create hot lava when you heat iron up this way; chances are, you’re not in the business of making a personal volcano.

Blunt force poses issues for magnetic fields, as well. The saving grace here is that blunt force damage to a magnet is avoidable if proper precautions are in place.

Small, weak magnets are most susceptible to this type of damage, and even then, you would have to throw it really hard or hit it with all of your might with a hammer to disrupt the magnet, irreparably.

The logic here is the same for why you do not want to raise a magnet’s temperature above the Curie point: a magnet’s function relies almost solely on its structure.

Keeping the integrity of the North and South poles that are produced when you magnetize an object is key - if you bend, drill, or break a magnet, you can easily disrupt this balance.

Finally, the volume of the magnet is important to factor in if you are considering whether re-magnetizing is worth it. Unfortunately, this falls under the auspices of structural damage, this time even more permanent.

Losing a chunk of your magnet due to extreme sudden blunt force changes the volume, obviously, but volume loss can also occur in less visible ways.

Like any metal, magnets are prone to corrosion if they are not handled properly.

Even losing part of the overall structure to corrosion weakens the force exerted by a magnet, and it is near impossible to fix without scrapping and remaking a magnet altogether. Wear and tear are serious problems, and that is why it is advisable to research the best magnet storage practices.

If none of these circumstances apply to you, then congratulations! You can (in theory) restore your magnet to its previous strength.

Permanent magnets that are in good condition, but have simply been weakened, can be restored when exposed to strong magnetic fields -- the best part is that you do not have to do this more than a few times.

Permanent magnets by definition will retain their field once removed from a strong magnetic field, and can be used to restore other magnets as well!

Electromagnets can rapidly regain their initial field if a current is run through their coils, and this is what makes these types of magnets so well-preserved in the long run. Electromagnets are still susceptible to damage, and if their coils are destroyed or the loop is disrupted, the magnetic field will too be eliminated.

How to Re-magnetize a Magnet

Let’s imagine that you’re all set to go magnet fishing, when you notice your magnet is weak and doesn’t carry the same kind of hold it usually has. Unfortunately, this is a reality many magnet-owners face, whether it be due to the reasons above, or improper storage.

Thankfully, re-magnetizing is just as easy as de-magnetizing. It is a process that requires only a few items that you probably have lying around anyways.

All you need are two things: a non-spherical neodymium magnet and a compass. Okay, you probably don’t have high-grade neodymium magnets with you, but they’re quick to obtain and can be purchased for a reasonable price online!

Neodymium is going to be your magnet of choice because it is one of the strongest magnets commercially available for personal uses: it is an alloy of neodymium, boron and iron. You can buy them online for under $30, and they have a multitude of orientations available.

The catch here is that you do not want to purchase the highest grade or largest type of neodymium magnet for safety reasons, but an average-sized, workable kind will do perfectly for re-magnetizing.

The compass is needed so you can determine the neodymium magnet’s polarity, if it is not already marked. You don’t want to use a spherical shape magnet, since it’s hard to detect their North and South sides without a lot of extra work, so keep it simple.

Here is how you can re-magnetize a magnet using Neodymium:

  • Step 1: Use the compass to determine the north and south forces of your magnet.
  • Step 2: Use the compass to do the same to your weakened magnet.
  • Step 3: Hold the south end of your old magnet to the north end of the neodymium magnet, and vice versa.
  • Step 4: Repeat Step 3 several times until your old magnet can retain its original polarity.

But say you have an electromagnet on your hands? Electromagnets differ slightly from permanent magnets as they require a coil and an electric current to activate their magnetic field.

These coils are often wrapped around a ferromagnetic material like steel in order to increase the magnet’s pull.

Re-magnetizing electromagnets requires a constant source of energy to provide a current to the coils.

They do not require a ton of effort to re-magnetize if you have access to this type of power source, but otherwise, a professional should look at your magnet to restore it.

Hence, you don’t want to suddenly pry open your car hood and play with the electromagnetic coil yourself!

Using high-voltage power sources can be dangerous without proper training, and depending on the intended application of your electromagnet, it may not be worth it to try reviving.

Once you have repeated these steps with as many permanent magnets as you need, proper storage is critical towards making sure your magnets stay charged.

There are multiple ways we can keep our magnets strong, and we will explore this topic in the next section.

Let’s say you’ve finally re-magnetized your magnet, and you want it to last for as a long as possible. There are additional steps you can take to ensure your revitalized magnet stays strong and usable for many years.

How Long Do Magnets Usually Last?

When talking about temporary magnets, you’re in the ballpark of anywhere between ten seconds and five minutes. For electromagnets, they will last as long as you can keep power circulating in their coils.

When talking about brand new, permanent magnets, the answer is: for as long as you want! Permanent magnets by definition will never lose their magnetic field unless they experience any of the problems previously mentioned.

Well-stored neodymium magnets will lose a small portion of their magnetism every century or so.

Even permanent magnets that had to be re-magnetized will be expected to keep their magnetic field for just as long as their initial field - it is one of the interesting properties of our universe that allows these magnets to maintain their function for impossibly long amounts of time.

However, all magnets are subject to damage if they are handled the wrong way; their shelf life is determinant on how often they are used, and how they were stored. Like any object, the more you use it, the more you risk damaging it.

Here are some helpful tips for extending the life of your magnet:

  • Store your magnets where the poles alternate if they are in the same drawer.
  • Protect your magnet from the elements when they are not being used
  • Always practice proper safety procedures when working with your magnet

Do not let your children or untrained hands play with your magnets, especially if they are powerful magnets that pose risk of bodily injury.

The alternating orientation means that if you have a bunch of bar magnets with North and South clearly labeled, store them in an alternating fashion where each North of one magnet is paired with the South of another, and vice versa.

Doing so will minimize the contact your magnets will have to opposing forces, and preserve their orientation for longer. You could also store each individual magnet separately, but depending on your space and frequency of use, this may not be so practical.

This should be obvious, but make sure your magnets are kept safe from the elements. Constant use of neodymium magnets for magnet fishing can wear the protective nickel coating away, and rust can result.

Rust will undoubtedly corrode the strength of your magnet as the iron inside will oxidize; as iron is the bulk of the magnetized material, less iron means less force.

Perhaps even more importantly, you do not want a safety hazard to be the reason you need to retire your magnet.

There are reports of people being injured by magnets, not so much the magnet itself, but the force that strong magnets exert on other objects. In strong magnets like those found in MRI machines, the force can be so strong that people can be suffocated or crushed to death.

It is especially advised to not allow children to handle your magnets, as there are reports of children swallowing magnets and ending up in the emergency room.

Swallowing one magnet is not usually a cause for concern, but if someone ingests multiple neodymium magnets, the force they exert on one another in the gastrointestinal tract can wreak havoc on the human body.

At the end of the day, a magnet will last only as long as you treat it well. Proper storage and safety are a must if you plan on using your magnet for many years to come.

The world of magnetism is a rapidly-evolving, constantly expanding field that is worthy of study.

One of the best parts is that anyone can observe and test the science of demagnetization and remagnetization, often sparking further curiosity into magnets and their various applications across our globe.