Make Your Own Liquid Magnets


Here is a nice followup to yesterday’s video: How to make your own ferrofluid. This guide comes from Dr. Anne Marie Helmenstine at The fine folks at Sci-spot seem to have the original with pictures. The composition of ferrofluid by volume is about 5% magnetic solids, 10% surfactant, and 85% carrier. The surfactant is what keeps the particles from sticking together permanently. Ferrofluids are often used for damping speakers and in disk drives. This procedure doesn’t seem to complex and one of the main components is ferric chloride, a.k.a. PCB etchant. Thanks go to [Jason Uher] who sent in this tip and says that it has worked out quite well for him in the past.

[photo credit]

26 thoughts on “Make Your Own Liquid Magnets

  1. I have never been a fan of until today. I usually find lots of their unrelated articles when doing a search for something. This article is great, I have never played with ferrofluid because it is so expensive. I think one of my next projects now is to make a batch of the stuff. Thanks!

  2. Could this stuff be used for a magnetohydrodynamic generator? It sure looks a lot safer than molten sodium. if it holds enough magnetic field then it could be run through coils of wire and generate electricity.

    Or, could I use magnets to pump this stuff and make a hydraulic power system with no moving parts in the pump?

  3. Does anyone know if olive oil can be substituted for oleic acid? The vendor at our campus chemical store said that they don’t sell oleic acid to anyone without a license since 9/11.

  4. That’s cool, I was poking around for a way to make this stuff when I saw yesterday’s post. That surfactant looks like its key to making it last without getting all clumped up.

  5. What about the laser toner and mineral oil mentioned in the comments in the last post? Does anyone have any more info on that? Surely it can’t be as good as this…

    Both promise some messy-good science, though!

  6. I attempted to make the ferrofluid today, but made a few substitutions — i’m not sure if they affected the outcome — the FF I made was cool and behaved somewhat like FF, but seemed to clump a little more.

    First, I subbed olive oil for oleic acid. according to wikipedia, olive oil is 55-80% oleic acid — so i assumed 66% and added 7.5ml of it. the reesultant FF seemed to clump so perhaps the oleic acid isn’t available for the reaction.

    I also tried a few different solvents b/c i didn’t have any kerosene available. I used oderless mineral spirits, glycerin and parrafin lamp oil. I had successful seperation using the mineral sprits and the lamp oil. Not so w/ the glycerine. The lamp oil version was nice b/c it didn’t stink.

    Finally, i followed the recomendation for 150mL of ammonia. I don’t know if my ammonia was lower molar concentration b/c when i added 150mL, the solution remained a medium brown (I cooked it for a while this way). . Upon adding another 50mL or so it went to the normal FF black. I’d suggest titration to black in your instructions…

    I have some oleic on order (….(now to make the magnetic coil winder for a grid of coils, some H bridges to drive em and a microprocessor to control em…)

  7. My vote is for the magnetohydrodynamic system!

    After some personal testing, I have determined that Dunkin Donuts Turbo Hot Espresso-Enhanced Coffee, while most certainly energetic, doesn’t contain nearly enough ferrous material to be considered for this application.

    It’s good though.

    …yes, have some.

  8. a fantastic source of the magnetite required for this reaction (for those who are lucky enough to live near the coast) is your run-of-the-mill beach sand. magnet + patience + a beach with really fine grained sand = as much magnetite as you could ever want. collect, and then pulverize the magnetite slightly if you want smaller particles, and you’ve yourself a perfect start for ferrofluid. i’ve done this, and i guarantee it works.

  9. If you need some oleic acid and want to have some fun AND are somewhat comfortable/have access to an O-Chem lab, just take some ground beef (the cheaper the better), cook it, strain and keep the fat (which has a great deal of Oleyl alcohol), combine this fat with some Chromic acid (or if you can’t get that, Potassium dichromate, sulfuric acid, water, and a little of heat will work), which should oxidize the Oleyl alcohol enough to give you a good amount of oleic acid. None of those ingredients should be hard to obtain.

    Of course, I think it’s preposterous that anybody tells you that oleic acid is a restricted substance. It’s a FATTY ACID.

  10. actually i made some with canolla oil, stayed good for atleast a few months(although i had to remix it since the toner sunk after a while)
    works really good but it can stain GLASS if it drys on it, and cement, nothing can clean it off
    so whatever you do with it, dont get it on anything ya care about
    and for ll the wouldbe pranksters uhh…. no idea, just dont get in trouble
    im going to try making some with motor oil later though, if it works i’ll make a video and post on youtube or somthing with full instructions

  11. I started looking into printer/copier toner for a ferrofluid since some one mentioned it. Not all toners have magnetite in them.

    Looking at the MSDS for various toners, for example the toner for my cheap samsung uses carbon as a pigment where the toner for an HP LazerJet 4 is 45-55% iron oxide (magnetite) and 45-55% styrene acrelate copolymer. [percent by mass]

    I don’t know it the polymer make’s it “less good” for a ferrofluid, but I think you could disolve it with xylene/toluene (solvents listed on the MSDS) and maybe filter, repeat a few times, to get just magnetite powder.

  12. I really dnt know what to tell bout this. m in 12th at present nd made this liquid magnet as a project in chemistry… nd must say that it is damn succeesful… may b coz india made all materials available to me very easily… to all those who r thinkin of makin this, i just wanna tell u tht please go ahead…. what u only need is a bit of patience nd a positive spirit..

  13. we are trying to make a ferro fluid using magnetic laser jet toner powder and canola oil as medium in about 1:1….its a disaster
    do we need a surfactant ?
    and is it better to use kerosene?
    please help

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