Is Cast Iron Magnetic? (Explained)
When using cast iron stovetops and other tools, you may wonder if you should worry about magnetism.
Strong magnets and electronics, for example, tend to have a poor relationship.
You may also wonder if you can use a strong magnet to store your cast iron items on the wall.
Here’s everything you need to know about whether cast iron is magnetic or not.
Is Cast Iron Magnetic?
Yes, cast iron is magnetic.
Iron is a magnetic metal because it has a large number of electrons that spin in the same direction.
To understand magnetism, you first need to understand the structure of a substance.
Every substance consists of atoms.
At the heart of each atom is a nucleus.
Spinning around the nucleus are electrons that carry an electric charge.
In some substances, the electrons spin in different directions.
This makes the atom well-balanced and doesn’t cause much magnetism.
Examples of such substances are things like paper or cloth.
Some substances have electrons that spin in the same direction.
Iron is a primary example of such a substance.
Because iron’s electrons spin in the same direction, they’re easily attracted to other substances that have similar electrons spinning in the same direction.
Cast iron is really no different than standard iron aside from a bit of extra carbon in it.
The term “cast” refers to the fact that someone smelted the iron ore into its liquid form.
Then they poured the liquid iron into a mold.
From that mold, they cast an object.
Hence the name, cast iron.
Some of the most common cast iron objects are pans, pots, and other cooking tools.
Since the tools are primarily made out of iron, they are, technically, magnetic.
However, to experience that magnetism, they need another magnetic substance to enter their magnetic force.
This makes the electrons interact with one another.
If they align two opposite poles together, the cast iron tool will become attracted to the other substance.
If they align two of the same poles together, the cast iron will repel the other substance.
You can play around with magnets and your cast iron items since cast iron is magnetic.
What Metals Are Magnetic?
Because iron is a highly magnetic metal, you may wonder what other metals share these magnetic properties.
It all has to do with how ferrous something is.
Ferrous refers to the amount of iron in a substance.
If the substance contains iron, it’s likely going to be magnetic.
That’s because iron itself is very magnetic.
Here are some examples of popular metals that are also magnetic.
1. Galvanized Steel
To make galvanized steel, the steel object receives a layer of zinc on its surface.
Zinc isn’t ferrous and isn’t a magnetic metal.
Because of that, you may think that galvanized steel isn’t magnetic.
That isn’t the case.
Galvanized steel is magnetic because most of it contains steel.
Steel is essentially iron that has some carbon added to it.
To become steel, no more than 2% of it should be carbon.
If there’s more than 2% carbon in the material, then it actually becomes cast iron.
Because steel is really just iron with a bit of carbon, it’s magnetic.
There isn’t enough carbon to disrupt the iron’s magnetic properties.
The other aspect of galvanized steel that may make you think it’s not magnetic is the zinc coating.
Because zinc isn’t magnetic, you may think that it, along with the carbon, would cancel out steel’s magnetism.
This isn’t the case because the coating of zinc is very thin.
It’s so thin that it doesn’t disrupt the underlying capability of steel to become magnetized.
Zinc is a great way to reduce steel’s tendency to rust when exposed to moisture.
If you’re using galvanized steel to make electronics, then you’ll want to keep in mind that it’s still magnetic.
2. Hot-Rolled Steel
Another popular type of steel that you’ll see used in various applications is hot-rolled steel.
This is steel that gets subjected to extremely hot temperatures.
While it’s under those temperatures, it’s rolled and then formed into the shape that it needs to be.
As the steel cools, it becomes rigid and durable.
Some manufacturers use this method to make steel that needs curved corners or rounded edges.
Because it goes through extremely hot temperatures, you may think that it disrupts the steel’s magnetic capabilities.
This isn’t the case.
Because it’s still steel, just steel that has cooled after being extremely hot, it retains its magnetic properties.
Steel is ferrous, and since nothing gets added to the steel for hot-rolling, there aren’t any other substances interfering with its magnetic qualities.
3. Stainless Steel
When it comes to stainless steel, determining if it’s magnetic or not is a bit murkier.
That’s because stainless steel gets mixed with chromium to make an incredibly durable new metal.
It’s also more resistant to corrosion, which makes it ideal for moist environments or environments with harsh chemicals.
Because it contains chromium, not all grades of stainless steel are magnetic.
It mostly depends on how much iron the steel still possesses.
For example, ferrous stainless steel is magnetic.
Martensitic stainless steel is also magnetic.
In industrial classifications, this is the 400 series of stainless steel.
Once there starts to be more chromium than iron, the stainless steel isn’t as magnetic.
4. Wrought Iron
Like cast iron, wrought iron is another type of iron with very low carbon content.
Because it doesn’t have that much carbon in it, it has a strong magnetic force.
The purer that the wrought iron is, the more magnetic it’s going to be.
Wrought iron is an ideal type of metal because it’s easily melded and shaped.
You can reheat it and let it cool over and over without damaging the material.
If anything, it makes wrought iron even stronger.
The purer that the iron is, the less prone to corrosion it is as well.
Due to the ease in shaping and forming this material, wrought iron is a popular type of metal to make various electronic parts and other industrial parts.
Which Metals Are Not Magnetic?
While it’s clear that the more iron that a type of metal has, the more likely it’s going to be magnetic, the opposite is also true.
Several types of metal don’t contain iron.
You may wonder if these are magnetic, too.
In most cases, they are not.
Here are some metals which are not magnetic.
1. Austenitic Stainless Steel
Like standard stainless steel, austenitic stainless steel isn’t magnetic.
That’s because it contains more austenite than iron.
Austenite is not magnetic.
Austenitic stainless steel doesn’t have enough iron to be magnetic.
That said, someone can alter austenite to create iron.
If someone were to do this, then they could make austenitic stainless steel more magnetic.
Albeit, it wouldn’t have a very strong magnetic force.
2. Aluminum
Another metal that isn’t magnetic is aluminum.
Aluminum has a crystalline structure similar to both magnesium and lithium.
The structure impedes this element’s ability to become magnetized.
That said, if you were to bring in a strong enough magnet, you may see some traces of magnetic reactivity with the aluminum.
Under normal conditions, however, aluminum is not magnetic.
3. Copper
Copper is an interesting metal because it has the properties that should make it magnetic, but it’s actually the opposite.
Along with needing electrons to spin in the same direction, a magnetic force also requires electrons to be in the outer shell of the atom.
Essentially, it needs a free electron in the outer shell.
Copper has a free-standing electron in its outer shell.
The problem with copper is that it interacts with other atoms of copper around it.
When the copper atoms get close to one another, the extra electron they have gets sent into a cloud.
The cloud makes the copper atoms form a metallic bond with one another.
That, in turn, makes the copper diamagnetic.
Something that is diamagnetic will actually repel a magnetic field.
Does Cast Iron Rust?
Yes, cast iron does rust.
Because it’s pure iron, with a bit of carbon in it, it’s subject to corrosion.
This occurs when the metal gets exposed to water.
It forms a chemical reaction which you see as rust.
How To Prevent Cast Iron Pots From Rusting
If you start to see some rust on your cast iron pots and pans, you may worry that its time is over.
That isn’t necessarily the case.
You can prevent the rust from spreading further and even keep rust from growing on your cooking tools in the first place.
Here are a few ways you can prevent rust from growing on your cast iron cooking tools.
1. Avoid Soaking The Pan
Cast iron and water should avoid one another like the plague.
If you want to use water to clean your pan, then you’ll want to use it sparingly.
You should never soak the pan in water, for example.
Instead, spray a little water in certain areas.
2. Dry Off Immediately
If you do use water, then you must dry it immediately and very thoroughly.
It’s when the pot gets exposed to the air after water exposure that the oxidation process begins.
If you can quickly use a cloth to wipe it dry, then you can disrupt the chemical reaction occurring between the water, the air, and the iron.
3. Use Oil
The best way to prevent your cast iron pot or pan from rusting is to keep it oiled.
Use vegetable oil and spread it thinly over the pot or pan.
This will keep the pot or pan moist without using water.
4. Season The Pan First
Before you start using tomato-based products or vinegar in your cast iron pot or pan, you’ll want it to get well-seasoned.
That’s because tomatoes, vinegar, and other acidic-based foods can also cause the cast iron pan to rust.
Seasoning your pan or pot with oil and getting a sanitary crust on it can protect it from acidic food.
Only once it’s well-seasoned should you start cooking tomato sauce and acidic foods in it.
5. Use It Often
A final way to prevent rust from growing on your cast iron pan is to use it.
When you put the pot or pan away and leave it alone for a long time, it starts to rust on its own.
That’s because the air around it can sometimes hold enough moisture to start the rusting process.
Those who live on the coast may also have a lot of salt in the air.
That can also cause the pot or pan to rust.
By using it frequently, you keep exposing it to oil and other seasonings which keeps it protected.
How To Remove Rust From Your Cast Iron Pan
If your cast iron pan is already rusty, you may worry that it’s beyond salvation.
That isn’t always the case.
With a bit of time and elbow grease, you can restore your cast iron pan.
Follow these steps to remove rust from your cast iron pan.
1. Vinegar Soak
If your pan has a lot of rust on it, you’ll want to start with this step.
If it doesn’t have that much rust on it, then you can skip to the second step.
For those who do have a very rusty cast iron pan, you’ll need to fill your sink with vinegar.
Then submerge the pan into the sink and let the vinegar eat away at the rust.
You’ll want to babysit this process because if you let the vinegar eat away at the pan too long, then it will start to eat holes into it.
At that point, your pan will be useless.
The soaking may take as long as eight hours or as little as a single hour.
You’ll want to remove the pan from the soak when most of the rust is gone.
2. Scrub It
The next step is to scrub the pan.
You’ll want to use a strong scrubber but one that isn’t too abrasive.
A microfiber cloth may do the job well.
Since the vinegar ate away at the seasoning on the pan, it’s safe to use soapy water on it.
You’ll want to scrub by hand and not put it in the dishwasher.
Use warm water and mild dish soap to scrub the remaining rust from your pan.
The warm water will dry faster on the pan which is important in preventing more rust build-up in the future.
Once you’ve scrubbed the remaining rust away, it’s time to preserve the pan to avoid further rust growth.
3. Dry And Heat
The first thing you need to do is dry your pan as fast as possible.
You can do with that a dry rag.
To speed up the process, you can put your cast iron pan in a warm oven.
The oven will dehydrate the pan and do an effective job of drying it fast.
4. Re-Season
The next thing you need to do to prevent rust from coming back is to re-season your cast iron pan.
The best way to re-season your pan is to cover it with vegetable oil and put it in the oven.
First, you’ll want to put a sheet of aluminum foil on the rack.
Then smear a very thin layer of oil all over the pan including the outside.
Next, you’ll want to turn the pan upside down and let it rest on the foil.
Set the oven to 350 degrees Fahrenheit, then let the pan sit in the oven for an hour.
Turn off the oven, and let the pan cool down for at least another 45 minutes.
After that, you can store your pan in a cool and dry place.
Your pan will be rust-free and protected from rusting again in the future.
Conclusion
Cast iron is magnetic because iron is a strong magnetic substance.
Other materials mixed with iron are often magnetic as well.
You can clean off rust and prevent the growth of rust on your cast iron tools by following the steps and tips above.