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

ferromagnetic fluid!

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!

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Step 1: Supplies

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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.

Step 2:

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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

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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

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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.

CrayfishYAY made it!2 months ago

I remember when I was in Alabama, I went outside & used a magnet to collect magnetic rocks. Then I spent long & tedious hours to finally get magnetic powder. I mixed the powder w/ vegetable oil, stuck 3 "sizzlers" under the plate, & this is the result:

Photo02121216.jpgPhoto02121214.jpgAwesome Ferromagnetic Material In Oil.jpgAwesome Ferromagnetic Material In Oil 2.jpgAwesome Ferromagnetic Material In Oil 3.jpgAwesome Ferromagnetic Material In Oil 7.jpgAwesome Ferromagnetic Material In Oil 8.jpgAwesome Ferromagnetic Material In Oil Negative.jpgAwesome Ferromagnetic Material In Oil Negative 2.jpgAwesome Ferromagnetic Material In Oil Negative 3.jpgAwesome Ferromagnetic Material In Oil 4.jpgAwesome Ferromagnetic Material In Oil 5.jpgAwesome Ferromagnetic Material In Oil 6.jpgAwesome Ferromagnetic Material In Oil Negative 4.jpg
mikeasaurus (author)  CrayfishYAY2 months ago

Wow, that's a cool story. I love that you had to find your own iron to make this. Thanks for sharing!

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violingirl made it!2 months ago

Thanks for this great project.

mikeasaurus (author)  violingirl2 months ago

Thanks for sharing your version. I hope you still have fun playing with it.

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dcq324 months ago
What is the procedure for the disposal of the fluid
mikeasaurus (author)  dcq324 months ago

You want to dispose of it? I still have mine at my desk to play with.

If you must get rid of it, since it's just a small amount of iron pigment, you could dispose of it in dirt.

lirvine4 months ago
How well would this work if I scaled it down? I am wanting one as a keyring so I've got something to fiddle with ?
ottermann7 months ago

Can you mix up a batch with the mineral oil, then put a small amount in a vial and fill the vial the rest of the way with more oil? If you do, does the 'blob' retain it's cohesion? Or does it dissipate?

mikeasaurus (author)  ottermann7 months ago

Excellent question!

While making this Instructable I experimented with a few different mediums to suspend the iron oxide powder; Alcohol, acetone, water, and mineral oil.

I found that the mineral oil was too viscus and suspended the powder making the fluid cloudy. Here's the picture of my results.


Hey Mike, is there any performance variance between the natural and synthetic Fe3O4? I know there is a large variance in particle size but wasn't sure if it was of consequence for this type of experiment. - Thanks in advance for your time and consideration.

Oil comes in many different viscosities which could be experimented with. Car engine oil would probably be too thick and dark. A light "sewing machine oil" might work well, or how about "baby oil" ?

Perhaps even your thick oil might clear if a magnet was left beside it for a while ? And in oil, would even plain iron filings work OK ?

THIS is almost a ferro magnetic fluid

That is the same exact thing I thought...Would it work?

laffinm6 months ago
Could it be possible to use fine shavings from a file to be used for this, or would they be too large?
Magitor7 months ago

This is not a ferromagnetic fluid....

Azzurro Magitor7 months ago

I agree. this is just ferromagnetic stuff in fluid.

Laral Magitor7 months ago

It is absolutely a ferromagnetic fluid by definition. What it is not is ferrofluid. There's a difference.

Magitor Laral7 months ago

Actually the word ferrofluid is portmonteau of the ferromagnetic fluid. A fluid wich has ferromagnetic property.

Laral Magitor7 months ago

Mere semantics. The word ferrofluid is in common use so it is well understood what it refers to. That's what both you and tallest are referring to. And, of course it's better than this but so what? Try making some…

the term 'magnetic powder suspension' is also in common use, and actually correct, unlike ferrofluid

Huh? Show me one reference that uses magnetic powder suspension and then use it in a sentence. What do you mean by "actually correct, unlike ferrofluid"? Sounds like utter nonsense to me…

tallest Magitor7 months ago

Agreed, I have the real deal; and this, while cool, is not the same. The real stuff uses nanoscale magnetite coated with a surfactant to prevent clumping, and is much thinner in consistency than the mineral oil stuff here. The particles of magnetite used in this instructable are too big and uneven, and without the surfactant the fluid won't move right when a magnetic field is applied.

This project could still be a good way to introduce kids to the basic concepts involved though.

MaggieS17 months ago

Hey! Could someone please tell me what this really is if it's not a ferromagnetic fluid/ ferrofluid? My knowledge in chemistry is pretty basic but I would love to show this to my classmates in school actually knowing what I'm talking about!

Also, does the water stay clear or will it get cloudy over time? Will it have the same effect in oil? And if I don't add anything to it?


jwhitley MaggieS17 months ago

Unfortunately, the title is a bit misleading. This is not actually ferromagnetic fluid, it is a ferromagnetic material (iron oxide) in a fluid medium (as Mike mentions in his comment here). A ferrofluid is usually made by using nanoparticles suspended in an oil. The entire medium moves in reaction to the presence of the magnetic field rather than just the ferrous particles. Unfortunately, making nano-scale, highly-round particles of iron turns out to be very difficult and expensive. It's also nearly impossible to get off of you because of the type of oil used. For an example of what it looks like and how it acts, see:

this must be the only correct piece of information in this whole instructible

mikeasaurus (author)  MaggieS17 months ago

It's ferrous powder in a fluid medium. It's an inexpensive DIY approach to visualize magnetic fields.

I've made a few, and the one sitting on my desk for 2 weeks is still clear. You should see my reply to otterman in the comments on my experiments with oil as the carrier in a jar (hint: oil works better on a flat surface as I show in Step 6-7 of this project).

I'd love to see your results!

Oh I didn't realize there were more steps! That is pretty amazing.
I'm already looking up where I can buy this. Thanks for the reply!

Laral7 months ago

Hey Mike, though you never answered my PMs, I see you went and bought the Fe₃O₄ from AlphaChem that I recommended. I have made liquid demonstrators like this with mineral oil, water, and alcohol, but I find that just containing the powder dry, in a sealed container works best. It allows more freedom of motion and awesome spikes and manipulations. I have also used, dry and wet, the really cool magnet powders, both alnico and NIB, from SuperMagnetMan. I find that dry works best and I prefer the alnico because it glistens and does not dust up the plastic like the NIB does.

avonborowsky7 months ago

Doesn't it get stain with time because of the water?

jcraig20 made it!7 months ago

This stuff is cool to play with especially if you have lots of magnets and kids and a place that you don't mind getting messy.

Magnet Fluid 1.jpgMagnet Fluid 2.jpg
Verticees7 months ago

I like the GIFS you included to show its behavior! Awesome!

文邱 made it!7 months ago

I made it last year, but I add glycerin in the container.

Jan_Henrik7 months ago

:( "Chemicals" are not sold to germany, but nice project!

tominjose7 months ago

cool, instead of fe3O4 i used magnet powder.