Making Ferrofluid

[The Thing]

Does anyone know how to make a passable to good quality ferrofluid (magnetorheological fluid (sp?))? I know of the crude iron filling to vegetable oil method, but I've heard that it doesn't work. Are there better methods?

Thanks.

[Caver451]

Does anyone know how to make a passable to good quality ferrofluid (magnetorheological fluid (sp?))? I know of the crude iron filling to vegetable oil method' date=' but I've heard that it doesn't work. Are there better methods?

Thanks.[/quote']

 

Yes, I've found a few procedures with not-too-difficult to obtain chemicals. However, I've never managed to get any spiking. I have some ideas why, but the stuff is so messy and ruins anything you use to make it that I got tired of throwing out glassware.

 

If you're just interested in playing with the stuff, you can actually buy it.

 

http://www.unitednuclear.com/magnets.htm

 

It is called MagnaView. United Nuclear is a trustworthy outfit.

 

If you really want the messy and frustrating experience of making it yourself, try...

 

http://chemistry.about.com/od/demonstrationsexperiments/ss/liquidmagnet.htm

 

I recommend putting in less kerosene than the procedure calls for, and slowly adding more until you get spiking. I think I put too much in, and it won't spike if you have too little or too much.

 

Oleic acid can be found in small quantities ($3.75/30 mL) at:

 

http://www.hometrainingtools.com/catalog/chemistry/chemicals/chemicals-m-p/p_ch-oleic.html

 

These guys seem trustworthy as well.

 

Good luck, and if you try to make some yourself, let us know how it turns out!

 

-Caver

[The Thing]

What happened to the ferrofluid that didn't get any spiking? Did it only show blobs?

 

What magnets did you use trying to get it spike?

 

Yea I found that site. However, where do I get some kerosene from?

 

Thanks.

[5614]

Home made ferrofluids will follow a magnet, not spike.

 

The type of magnet makes no difference.

 

I'm sure you can buy kerosene as a fuel.

 

You're far better off just buying some real ferrofluid that does spike - it's soo cool! And it really does stain everything - glass, plastic, skin, paper, you name it!

 

See here to see what I mean about staining:

http://img.photobucket.com/albums/v601/5614/ferrofluid1.jpg

http://img.photobucket.com/albums/v601/5614/ferrofluid.jpg

[Caver451]

My ferrofluid does indeed "blob", and the blob will follow your magnet anywhere. Tip: Put your magnet in a plastic bag when near ferrofluids, even the "blobbing" kind. Truuuust me.

 

It IS possible to create ferrofluid that spikes at home, just not with the "add powdered magnetite to oil and pray" method. You need to actually synthesis the magnetite yourself, and introduce the surfactant (oleic acid, in my case) at the proper step in the synthesis. And you need to have the correct amount of carrier (the kerosene) or it won't spike.

 

Kerosene can be found at any hardware store. Look in the solvent section--at my local Home Depot, it is stored with the paint thinners and other solvents. It is also used as fuel in kerosene heaters. Try to find it without dyes or perfumes. It's only a few dollars for more than you'll ever need.

 

My magnet is a neodymium disk magnet. You can find neodymium magnets at any good science shop.

 

The other thing you'll need is ferric chloride, which is about $8/liter. Again, more than you'll ever need. You can find it at any electronics hobbyist shop. It's used to etch circuit boards. Careful, it is toxic and it stains like crazy. You'll also need some steel wool to synthesis ferrous chloride from the ferric chloride. By at the grocery store (make sure it doesn't have soap already on it) or at the hardware store in the paint department. It's cheap. The finer you can find, the better. I used "#0000" grade wool, which is very fine for furniture refinishing. When you add the wool to the ferric chloride, it is an exothermal reaction which generates a good amount of heat--add a very tiny amount, mix until dissolved, repeat. I measured things out carefully, but ended up adding steel wool until there was no more ferric chloride to react with it. I recommend filtering the resulting ferrous chloride to remove the impurities introduced by the steel wool, as well as any left over steel wool.

 

Ammonia is a cleaning supply which you can buy at the grocery store, drug store, home store, etc. Make sure it is not dyed and has no added perfumes. The cheap brands tend to be better in that regard.

 

Have paper towels on hand, use rubber gloves (really!) and wear proper eye protection.

 

There are other ways to make ferrofluid, but the one I gave the URL for uses the safest and easiest to obtain chemicals. Even so, it is still toxic, so please be careful. This is an "oil based" formula. There are water based formulas, but I wasn't able to find any that didn't use difficult to obtain and insanely toxic surfactants.

 

One last tip: I suggest filtering your finished ferrofluid. Any magnetite which isn't in a death grip with the oleic acid is going to clump, will screw up your ferrofluid, and will make a major mess in your glassware. If you filter it, the clumping magnetite won't get through the filter paper, but the "good stuff" will flow right through.

 

-Caver

[5614]

And if you accidentally move the magnet above the ferrofluid (when there is no lid) in a way that the ferrofluid jumps up to the magnet, don't move the magnet up quickly, as the ferrofluid will follow it through the air - towards your face!

 

Not much actual volume makes it through the air... but still!

 

=====

 

When you get a bit of ferrofluid on a magnet (ie. a strong NIB one) it's cool because the liquid will not move because it is so strongly attracted, yet it is still liquid. It's like a hard liquid with a very slippery surface (if you stroke your finger across it), I've never felt anything like it. To clean the magnet you'll basically need something to rub the ferrofluid onto, paper towels seem to do the trick fine.

[The Thing]

Thanks Caver. I'll try to make this stuff in my school's chem lab on monday.

5614, I thought once ferrofluid gets onto a strong NIB magnet, its nearly impossible to get it off?

[Caver451]

Thanks Caver. I'll try to make this stuff in my school's chem lab on monday.

5614' date=' I thought once ferrofluid gets onto a strong NIB magnet, its nearly impossible to get it off?[/quote']

 

Not impossible. Just really messy. Scrubbing with paper towels will get it off, but it is a real pain, and you lose a lot of fluid that way. You can take much of it off one magnet with another, stronger magnet as well. Either way, it is a mess so you may want to keep your good magnets in plastic bags while working with the stuff.

 

Please, let us know how it turns out!

 

-Caver

[freddybaby]

I think blowing it off with a shop air hose is the best way, hold the magnet really close and give it a blast. A really great way to prevent "fouling" your magnets is to wrap them in a thin layer of stretchy plastic like Parafilm or even Saran warp, then you can clean and get of with the next experiment...

[hermanntrude]

I'm going to attempt this synthesis soon. I'm going to use pure paraffin oil and ammonia and oleic acid diluted from pure samples and the physics instructor has agreed to lend me the neodymium magnets.

 

Other than what's written above, does anyone have any tips? Will I get spikes do you think? Does it have a shelf life or will the colloid remain stable indefinitely?

[ironious]

I'm going to attempt this synthesis soon. I'm going to use pure paraffin oil and ammonia and oleic acid diluted from pure samples and the physics instructor has agreed to lend me the neodymium magnets.

 

Other than what's written above, does anyone have any tips? Will I get spikes do you think? Does it have a shelf life or will the colloid remain stable indefinitely?

 

I gotta know, did it work? Im going to make some too using oleic acid and kerosene. I thought about using polysorbate 20 because it also is a surfactant. However I was told that it would not work. Anyone know why?

[hermanntrude]

I havent yet tried it. I ordered the oleic acid from my local pharmacy but i wont be back in my lab till monday, and i might not have time ti try it out till later in the week. I am hoping that having a laboratory and some pure chemicals will help me get a better result. I will be disappointed if it doesnt spike. I also have access to some neodymium magnets which should help too.

 

There's another version which is water based but the surfactant is tetramethyl ammonium chloride, which you would definitely need a laboratory for.

 

I expect that most surfactants would do the job but the rest of the formulation would need to be "tweaked" to get the right consistency.

 

I'll let you know when it's done. What i'm hoping is that i can bottle it and bring it out every year as a demonstration.

[ironious]

I havent yet tried it. I ordered the oleic acid from my local pharmacy but i wont be back in my lab till monday, and i might not have time ti try it out till later in the week. I am hoping that having a laboratory and some pure chemicals will help me get a better result. I will be disappointed if it doesnt spike. I also have access to some neodymium magnets which should help too.

 

There's another version which is water based but the surfactant is tetramethyl ammonium chloride, which you would definitely need a laboratory for.

 

I expect that most surfactants would do the job but the rest of the formulation would need to be "tweaked" to get the right consistency.

 

I'll let you know when it's done. What i'm hoping is that i can bottle it and bring it out every year as a demonstration.

 

I got some oleic acid from ebay.Im waiting for it to arrive. You'd be amazed what you can find on ebay. There are several chemical companies that set up shop there. You can get the magnets and lots more from United Nuclear - Scientific Supplies Ive got the n45 neodymium magnets also. I dont have a lab, Im just doing this at home. I like the suggestion of running the final product through a filter 1 last time. I just hope hte filter doesnt soak up too much of the fluid though.

[hermanntrude]

well my first attempt didnt work. I found that making FeCl2 from FeCl3 and steel wool didn't work out. So I made some using HCl and iron filings, but i wasn't too careful about concentrations and I also used concentrated ammonia instead of dilute, and my magnetite flocculated. I think a magnetic stirrer bar might have been a mistake too.

 

Attempt number two will be made shortly

[ironious]

well my first attempt didnt work. I found that making FeCl2 from FeCl3 and steel wool didn't work out. So I made some using HCl and iron filings, but i wasn't too careful about concentrations and I also used concentrated ammonia instead of dilute, and my magnetite flocculated. I think a magnetic stirrer bar might have been a mistake too.

 

Attempt number two will be made shortly

I finished mine. When I added the ammonia it formed like a crystal or flake but from looking at the finished product, I can say that that is normal. After you boil off the ammonia it is throughly gummed into the oleic acid. When the kerosene is added, it dissolves the magnetite oleic acid solution into itself. Double filtering the finished did nothing because as far as I could see, nothing collected into the filter, If anything did collect then it was absorbed into the filter because when I was done, the filter was black. It didnt readily spike up when a megnet was placed next to it. BUT after playing with it for a while, I discovered that if you pull magnet away and fiddle with it, you can make it spike. I think the non spiking problem is because there is too much kerosene. I wasnt able to get pictures of the spikes because after I took a pictures, I didnt like them so I deleted them only to come back to find that my father had added more kerosene to the fluid with out asking me. He was thinking that it would help it spike better but now it will not spike at all. All that work and effort for nothing Ive got some sitting out in hopes that some of the kerosene will evaporate.

 

Also I would like to note that the instructions for this are not correct. After you boil off the ammonia, all of the magnetite will sink to the bottom. Now is the time to pour off the water, before you add the kerosene because they dont separate like the instructions said. I poured off most of the water first. But not all because the instructions said they would separate. Well they don't. They do separate after playing with the ferrofluid for a while but then you have to stick a napkin in the container to soak up the beads of water. I believe the oleic acid has something to do with the water and kerosene not separating.

 

I think a stronger magnet would work better also. Regular refrigerator magnets are worthless for this application.

[hermanntrude]

well done, ironius.

 

Tell me, how did you find the reduction of FeCl3 to FeCl2? I found that just adding steel wool and stirring didn't change the colour much at all. It's sposed to go green but it didn't for me.

 

By the way "kerosene" which is paraffin in real life, definitely doesn't mix with water. It might temporarily combine in a weird colloidal suspension under some conditions but if you leave it to stand it will always separate

[ironious]

well done, ironius.

 

Tell me, how did you find the reduction of FeCl3 to FeCl2? I found that just adding steel wool and stirring didn't change the colour much at all. It's sposed to go green but it didn't for me.

 

By the way "kerosene" which is paraffin in real life, definitely doesn't mix with water. It might temporarily combine in a weird colloidal suspension under some conditions but if you leave it to stand it will always separate

Ive been letting it sit for days now but it doesnt seem to want to separate at all Does the water sink to the bottom maybe? Like I said b4, I think its the oleic acid thats making the water colloidal. Polysorbate 20 is a surfactant and it will make water and oil mix. That how they make a lot of hand creams and lotions. In all honesty though, I dont know why the water and kerosene appear to be mixing. I am just guessing. I am not a scholar, Just your average guy that thought it would be cool to make some ferro fluid.

 

In answer to your question, just keep adding more steal wool. It takes quite a bit more then you would think. It will turn florescent green then an aqua green almost clear. Then Just pull the remainder of the steal wool out and give it a good squeeze to wring out all of the FeCl2. I kept adding small pieces but wasnt seeing hardly any change either. So I stuck a big piece in and got worried because the steal wool acted like a sponge and soaked most of it up; However the steal wool get broken down and its not too difficult to wring most of the liquid out of it.

I advise adding the ammonia under a vent hood or out doors. Because as soon as I did it, huge amounts of ammonia gassed off and burned my eyes, nose, and chocked me. And I didnt even poor it in all at once! I had it in a syringe and was was adding it several drops at a time as per a similar suggestion in this thread. Good fun here! I used Janitorial strength ammonia from Ace Hardware.Its 10% ammonium hydroxide.

[hermanntrude]

Ive been letting it sit for days now but it doesnt seem to want to separate at all Does the water sink to the bottom maybe? Like I said b4, I think its the oleic acid thats making the water colloidal. Polysorbate 20 is a surfactant and it will make water and oil mix. That how they make a lot of hand creams and lotions. In all honesty though, I dont know why the water and kerosene appear to be mixing. I am just guessing. I am not a scholar, Just your average guy that thought it would be cool to make some ferro fluid.

 

In answer to your question, just keep adding more steal wool. It takes quite a bit more then you would think. It will turn florescent green then an aqua green almost clear. Then Just pull the remainder of the steal wool out and give it a good squeeze to wring out all of the FeCl2. I kept adding small pieces but wasnt seeing hardly any change either. So I stuck a big piece in and got worried because the steal wool acted like a sponge and soaked most of it up; However the steal wool get broken down and its not too difficult to wring most of the liquid out of it.

I advise adding the ammonia under a vent hood or out doors. Because as soon as I did it, huge amounts of ammonia gassed off and burned my eyes, nose, and chocked me. And I didnt even poor it in all at once! I had it in a syringe and was was adding it several drops at a time as per a similar suggestion in this thread. Good fun here! I used Janitorial strength ammonia from Ace Hardware.Its 10% ammonium hydroxide.

 

thanks for the advice

[hermanntrude]

OK my second attept worked much better. I did as ironious suggested and added a ton of steel wool to my aliquot of FeCl3 and left it for a day to react. After filtration it was a lovely green colour. My magnetite was completely black this time instead of dark with an orange tinge, and my parrafin solution at the end was definitely magnetic, BUT... no spiking :'0(

 

very disappointed, although i might be able to improve it after letting it settle and decanting it again, perhaps diluting half of it, it's very viscous. Also I'm think that a large steel magnet might be better than a small neodymuim magnet

[ironious]

Im using a large neo magnet. 1" in diamiter by 2" long. My 1"x1" also works. I found that my smaller neo magnets are no good for this.

[hermanntrude]

yes these are about a quarter inch diameter. I guess i'll have to suck it up and order a larger one or get one out of a hard drive

[ironious]

yes these are about a quarter inch diameter. I guess i'll have to suck it up and order a larger one or get one out of a hard drive

They are not too pricey. I got mine on ebay for a little over 10 bucks. This is the one I got http://cgi.ebay.com/1-x-2-N45-Rare-Earth-Neodymium-NdFeB-Cylinder-Magnet_W0QQitemZ120235390316QQihZ002QQcategoryZ31485QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[hermanntrude]

I got some very strong ceramic magnets at Canadian tire. When i get back to my college, assuming my ferrofluid hasn't flocculated, i'll try it out.

[ironious]

I got some very strong ceramic magnets at Canadian tire. When i get back to my college, assuming my ferrofluid hasn't flocculated, i'll try it out.

 

Its going to flocculate some what when you add the ammonia, thats normal. If it gets rock hard then you must be doing something wrong. Try using a solution 10% ammonium hydroxide 90% water. Thats what Im using. Here's some stuff I been working on.

 

 

 

Yup. I did that, I made homemade ferrofluid spike.

[hermanntrude]

i'm gonna test mine today with a stronger magnet. When i said flocculate i meant AFTER synthesis, not during. I wonder how stable the colloid is.

 

no spiking. I know where i went wrong, though. I doubled my reactants but not the volume of the solvents, so i'm getting a lot of precipitation/flocculation.