ferrofluid magnetic experiment

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DIY Magnetic Ferrofluid from Scratch

Last Updated: December 14, 2024 References

This article was co-authored by Jessie Antonellis-John and by wikiHow staff writer, Hannah Madden . Jessie Antonellis-John is a Math and Science Instructor who teaches at Southwestern Oregon Community College. With over 10 years of experience, she specializes in curriculum development. Jessie earned her PhD in Teaching & Teacher Education from the University of Arizona, her Master of Education from Western Governors University, and her BS in Astrophysics from Mount Holyoke College. She’s also co-authored several peer-reviewed journal articles in professional publications. There are 7 references cited in this article, which can be found at the bottom of the page. This article has been viewed 22,898 times.

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.

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

• 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.

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

• 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.

Stir the mixture together with a stick.

• You won’t notice any immediate changes right away, and that’s okay. Just wait until you grab a magnet in the next step!

Place a magnet under the shallow dish.

• 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!

Store ferrofluid in an airtight container.

• 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.

Throw ferrofluid in the trash when you're done.

• Do not pour ferrofluid down the drain, as it will clog your pipes.

Community Q&A

• Iron oxide will stain clothes and surfaces. Be careful not to get it on your clothing or countertops during your experiment. [8] X Research source Thanks Helpful 0 Not Helpful 0
• 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] X Research source Thanks Helpful 0 Not Helpful 0

Things You’ll Need

• Stirring stick
• Airtight container

You Might Also Like

• ↑ https://www.youtube.com/watch?v=CWH9C__jn2w&t=287s
• ↑ https://www.youtube.com/watch?v=CWH9C__jn2w&t=271s
• ↑ https://www.youtube.com/watch?v=-ZoW7ayI9MY&t=173s
• ↑ https://www.youtube.com/watch?v=-ZoW7ayI9MY&t=216s
• ↑ https://www.businessinsider.com/how-to-make-ferrofluid-the-liquid-of-the-future-2012-1
• ↑ https://www.supermagnete.de/eng/faq/Questions-and-answers-about-ferrofluid
• ↑ https://www.youtube.com/watch?v=-ZoW7ayI9MY&t=134s

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Ferromagnetic Fluid

Introduction: Ferromagnetic Fluid

Magnetic silly putty was pretty awesome, but it's time to take it to the next level with

Making your own ferromagnetic fluid (ferrofluid) is super easy, and it uses the same easy to get black iron oxide powder as the magnetic putty. The best thing about ferromagnetic fluid is that there's many ways to make it. Depending what medium you add to the oxide powder it will react differently; a low viscosity medium like water will allow you to play with magnetic fields with immediate feedback, a higher viscosity medium like mineral oil will suspend the oxide particles and create beautiful sculptures of magnetic fields. I'll show you how to make both.

Ready to get polarized? Let's make!

Step 1: Supplies

Since we're working with paint pigment you'll need to protect your work surface, and wear protective gloves so you don't stain your hands.

Add a small scoop of iron oxide powder to a clean and dry glass container. You won't need much, about one half scoop for a 6oz (175ml) container.

Fill remainder of container to the brim with water. Don't worry about any dry pockets of powder after the water is poured on top, the oxide powder will eventually be saturated with water.

Step 3: Seal With Caulking

Playing with ferromagnetic fluid is super fun, spilling it isn't.

To protect against eventual spills a bead of silicone caulking is added to the threads of the container and the lid tightly screwed on, creating a waterproof seal. The container was left upright to cure for a few hours.

Step 4: Add Magnet

After the caulking has cured you're ready to play with your container of ferromagnetic fluid. Bring a magnet close to the container and watch the magnetic field become visible as the iron filings attract in the water medium.

Try hovering the magnet at different distances away from the container to create different visual effects, or try dragging the magnet around the container and watch the filings pile up.

Step 5: Ferromagnetic Fluid With Oil

Another great medium to display a magnetic field is in a neutral oil. This type of ferromagnetic fluid makes a blob-like creation with similar properties for viewing the magnetic field.

Along with the black iron oxide you'll need mineral oil and a thin plastic dish to hold your liquid (I used a lid from a take out container).

Step 6: Add Oil and Mix

Scoop black iron oxide powder onto your dish and pour mineral oil over, stir until mixed completely and there are no lumps.

Step 7: Introduce Magnet

Place magnet underneath the dish and watch as the viscus ferromagnetic fluid takes the shape of the magnetic field.

Mesmerizing!

Happy making :)

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How to Make Liquid Magnets

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A liquid magnet, or ferrofluid, is a colloidal  mixture  of magnetic particles (~10 nm in diameter) in a liquid carrier. When no external magnetic field is present, the fluid is not magnetic and the orientation of the magnetite particles is random. However, when an external magnetic field is applied, the magnetic moments of the particles align with the magnetic field lines. When the magnetic field is removed, the particles return to random alignment.

These properties can be used to make a liquid that changes its density depending on the strength of the magnetic field and can form fantastic shapes.

The liquid carrier of a ferrofluid contains a  surfactant  to prevent the particles from sticking together. Ferrofluids can be suspended in water or in an organic fluid. A typical ferrofluid is about 5% magnetic solids, 10% surfactant, and 85% carrier, by volume. One type of ferrofluid you can make uses magnetite for the magnetic particles, oleic acid as the surfactant, and kerosene as the carrier fluid to suspend the particles.

You can find ferrofluids in high-end speakers and in the laser heads of some CD and DVD players. They are used in low friction seals for rotating shaft motors and computer disk drive seals. You could open a computer disk drive or a speaker to get to the liquid magnet, but it's pretty easy (and fun) to make your own ferrofluid.

Here's how:

Safety Considerations

Fuse / Getty Images

This procedure uses flammable substances and generates heat and toxic fumes. Wear safety glasses and skin protection, work in a well-ventilated area, and be familiar with the safety data for your chemicals. Ferrofluid can stain skin and clothing. Keep it out of reach of children and pets. Contact your local poison control center if you suspect ingestion. There is a risk of iron poisoning; the carrier is kerosene.

jopstock / Getty Images

Here are the materials you'll need:

• Household ammonia
• Oleic acid (found in some pharmacies and craft and health food stores)
• PCB etchant (ferric chloride solution), available at electronics stores. You can make ferric chloride or ferrous chloride solution or you can use magnetite or magnetic hematite powder if you have either of those minerals handy. (Magnetic hematite is an inexpensive mineral used in jewelry.)
• Distilled water
• Heat source
• 2 beakers or measuring cups
• Plastic syringe or medicine cup (something to measure 10 ml)
• Filter papers or coffee filters

While it is possible to make substitutions for the oleic acid and the kerosene, changes to the chemicals will result in changes to the characteristics of the ferrofluid, to varying extents. You can try other surfactants and other organic solvents; however, the surfactant must be soluble in the solvent.

Synthesizing Magnetite

Ekaterina Lutokhina / Getty Images 

The magnetic particles in this ferrofluid consist of magnetite. If you aren't starting with magnetite, then the first step is to prepare it. This is done by reducing the ferric chloride (FeCl 3 ) in PCB etchant to ferrous chloride (FeCl 2 ). Ferric chloride is then reacted to produce magnetite. Commercial PCB etchant is usually 1.5M ferric chloride, to yield 5 grams of magnetite. If you are using a stock solution of ferric chloride, then follow the procedure using a 1.5M solution.

• Pour 10 ml of PCB etchant and 10 ml of distilled water into a glass cup.
• Add a piece of steel wool to the solution. Mix the liquid until you get a color change. The solution should become bright green (green is the FeCl 2 ).
• Filter the liquid through filter paper or a coffee filter. Keep the liquid; discard the filter.
• Precipitate the magnetite out of the solution. Add 20 ml of PCB etchant (FeCl 3 ) to the green solution (FeCl 2 ). If you are using stock solutions of ferric and ferrous chloride, keep in mind FeCl 3 and FeCl 2 react in a 2:1 ratio.
• Stir in 150 ml of ammonia. The magnetite, Fe 3 O 4 , will fall out of solution. This is the product you want to collect.

Suspending Magnetite in a Carrier

Westend61 / Getty Images

The magnetic particles must be coated with a surfactant so that they won't stick together when magnetized. The coated particles will be suspended in a carrier, so the magnetic solution will flow like a liquid. Since you will be working with ammonia and kerosene, prepare the carrier in a well-ventilated area, outdoors or under a fume hood. Follow these steps:

• Heat the magnetite solution to just below boiling.
• Stir in 5 ml oleic acid. Maintain the heat until the ammonia evaporates (approximately an hour).
• Remove the mixture from the heat and allow it to cool. The oleic acid reacts with ammonia to form ammonium oleate. Heat allows the oleate ion to enter the solution, while the ammonia escapes as a gas (which is why you need ventilation). When the oleate ion binds to a magnetite particle, it is reconverted to oleic acid.
• Add 100 ml kerosene to the coated magnetite suspension. Stir the suspension until most of the black color has been transferred into the kerosene. Magnetite and oleic acid are insoluble in water, while oleic acid is soluble in kerosene. The coated particles will leave the aqueous solution in favor of the kerosene. If you make a substitution for the kerosene, the solvent must have the same property: the ability to dissolve the oleic acid but not uncoated magnetite.
• Decant and save the kerosene layer. Discard the water. The magnetite plus oleic acid plus kerosene is the ferrofluid.

Things to Do With Ferrofluid

LYagovy / Getty Images 

Ferrofluid is very strongly attracted to magnets, so maintain a barrier between the liquid and the magnet (e.g., a sheet of glass). Avoid splashing the liquid. Both kerosene and iron are toxic, so do not ingest the ferrofluid or allow skin contact—don't stir it with a finger or play with it.

Here are some ideas for activities involving your liquid magnet ferrofluid:

• Use a strong magnet to float a penny on top of the ferrofluid.
• Use magnets to drag the ferrofluid up the sides of a container.
• Bring a magnet close to the ferrofluid to see spikes form, following the lines of the magnetic field.

Explore the shapes you can form using a magnet and the ferrofluid. Store your liquid magnet away from heat and flame. If you need to dispose of your ferrofluid at some point, dispose of it the way you would dispose of kerosene.

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