DIY Magnetic Ferrofluid from Scratch

Learn how to make your own ferrofluid and discover how it works

Co-authored by Jessie Antonellis-John and Hannah Madden

Last Updated: September 27, 2023 Fact Checked

Looking for a cool science experiment you can do at home? Look no further! Ferrofluid, or ferripaste, is an easy, fun-to-make magnetic oil that only needs 2 ingredients: motor oil and iron oxide powder. When you mix these 2 things together, it creates a special “fluid” that almost behaves like a solid, especially in the presence of a magnet. So what are you waiting for? To make your very own ferrofluid to play around with, read this article!

Things You Should Know

Mix 10 grams (0.3 oz) of motor oil with 10 grams (0.3 oz) of iron oxide powder in a petri dish.
Use a magnet to manipulate the ferrofluid to make peaks and valleys.
Because the iron oxide is magnetic and suspended in the oil, a magnet can manipulate it.
Store ferrofluid in an airtight container. When you’re done, dispose of the ferrofluid in the trash.

1

Pour 10 grams (0.3 oz) of motor oil into a dish.

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Motor oil is the carrier oil that will hold your fluid together. Measure out the motor oil using an electronic scale. Then, pour the oil into a shallow dish made of thin plastic, like a petri dish.^{[1]
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- The viscosity of the motor oil doesn’t matter here. As long as it’s motor oil, it will work!
- Petri dishes are ideal, because they’re thin enough for a magnet to penetrate.
- Some people have also had success using vegetable oil instead of motor oil. However, vegetable oil is very thin, and may not combine with the iron oxide as well.

2

Add 10 grams (0.3 oz) of iron oxide powder.

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Iron oxide powder creates the magnetism in ferrofluid. Use your electronic scale again to measure your iron oxide. Then, pour the iron oxide into the motor oil.^{[2]
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- You may have heard about harvesting iron oxide from cassette tapes using acetone. If you’d like to try this method, break apart cassette tapes and soak the tape in acetone for 1 hour outside. Then, use a knife to gently scrape the iron oxide off the tape into a dish. Just keep in mind that many people have tried this method with little success, so it’s a better idea just to buy iron oxide outright.
- You can also make ferrofluid with magnetic ink developer or ferric chloride, but these are very expensive. Iron oxide is much more affordable.

3

Stir the mixture together with a stick.

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Combine your ingredients until your mixture is thick. Use a stir stick that you don’t mind throwing away later, because iron oxide stains. Keep stirring until the ferrofluid is the consistency of a thick stew.^{[3]
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- You won’t notice any immediate changes right away, and that’s okay. Just wait until you grab a magnet in the next step!

4

Place a magnet under the shallow dish.

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Use a magnet to manipulate the ferrofluid. Since iron oxide is magnetic, it will automatically gravitate toward the force of a magnet. Place your magnet underneath the petri dish and move it around. Have fun playing with your ferrofluid!^{[4]
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- When the iron oxide mixes with the oil, the iron particles stay suspended in the fluid rather than mixing entirely. When you introduce a magnet to the ferrofluid, the magnet pulls the particles apart, forcing the fluid into interesting shapes, peaks, and valleys.
- Try moving your magnet to the side and the top of the dish, too. Just be careful not to dip it in the ferrofluid, or things could get messy!

5

Store ferrofluid in an airtight container.

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Keep ferrofluid around for a couple of months if you’d like to. Want to keep playing with your ferrofluid? Pour it into an airtight container that you don’t mind throwing away later.^{[5]
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- Ferrofluid only starts to break down when it’s exposed to air. If you keep it sealed in a glass jar, it has a shelf life of up to 10 years.

6

Throw ferrofluid in the trash when you're done.

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Dispose of ferrofluid like you’d dispose of motor oil. Since ferrofluid is mostly motor oil, it’s considered hazardous waste. For small quantities (like 1 batch), seal it in an airtight container and throw it in the trash. For large quantities (like multiple batches), take the ferrofluid to a hazardous waste facility.^{[7]
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- Do not pour ferrofluid down the drain, as it will clog your pipes.

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Warnings

Iron oxide will stain clothes and surfaces. Be careful not to get it on your clothing or countertops during your experiment.^{[8]
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Ferrofluid is highly flammable, and while it’s not toxic, it can cause skin irritation. If ferrofluid gets on your skin, rinse well with warm water for 15 minutes.^{[9]
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