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Please take a look at the following video:

Ferrofluid

I am working on a new project, and I need to find whats the best liquid to hold ferrofluid inside the glass (or maybe even plastic) container, so that ferrofluid (that easily stains everything) does not stain or stick to glass?

Also, is there any special preparation for the glass needed?

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    $\begingroup$ What is the ferrofluid you plan on using? $\endgroup$
    – F'x
    May 16, 2012 at 11:33
  • $\begingroup$ It is, FerroFluid EFH-1 by FerroTec Corp this one - amazingmagnets.com/show-decimal-ferrofluid-0250.aspx $\endgroup$
    – Damjan Stankovic
    May 16, 2012 at 12:42
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    $\begingroup$ I played with ferrofluids when I was younger. I don't recall them being particularly staining on pyrex? I don't know why borosilicate would be any worse off the top of my head. Are you sure a water mixture with this ferrofluid wouldn't work? It would stain the glass presumably? $\endgroup$
    – Chris
    May 17, 2012 at 20:34
  • $\begingroup$ I tried it, it stains the glass and leaves a trace.. if you go over it with a magnet few times quickly you might be lucky and remove the stain but if you leave it for some time its... painted :) $\endgroup$
    – Damjan Stankovic
    May 18, 2012 at 3:23
  • $\begingroup$ Definitely don't use plastic. I tried to make some ferrofluid back in high school, and it ended up melting the plastic and making a big mess. $\endgroup$
    – nhinkle
    May 18, 2012 at 16:48

4 Answers 4

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I had success with the following:

1) Glass bottle, ideally with flat sides. If you have a round bottle you may not be able to see the ferrofluid due to diffraction.

2) A solution of ~25% distilled water (a.k.a. deionized water) and ~75% of store bought isopropyl alcohol at 91% concentration. That means that ~70% of my solution was actually isopropyl alcohol. I eyeballed the ratio between the water and the isopropyl alcohol, those numbers are likely to not be exactly correct.

Procedure that I followed:

Add some isopropyl alcohol to the glass container. Then add some (or all) of your ferrofluid to the container. Then add some water to bring your isopropyl alcohol concentration to about 70%. Next, use a magnet to settle the ferrofluid to the bottom and then remove the magnet. If your ferrofluid has little bits that are floating, then you need to add more water. If your ferrofluid looks too stringy then I would add more alcohol. When I was done the ferrofluid had zero staining, like you see in the videos online, except for in a few spots. I think for better results I would need a higher quality glass container.

notes: Don't put too much ferrofluid in your container, otherwise you will have an uninteresting blob. I recommend using gloves. To clean the ferrofluid stuff off my hands I used warm water, laundry detergent, and lots of scrubbing with a towel. If you mess up, you can use a magnet to hold your ferrofluid in place while you pour off some of your suspension fluid. In addition, you can use a straw and your thumb to pipet some of the ferrofluid, however some will get stuck in the straw, so I wouldn't do that unless you have a bunch of ferrofluid. Finally, I only finished like 30 minutes ago, so I hope it will all look good tomorrow. If something bad happens I will make another post.

notes, part 2: If all you want is a cool desk toy, then I recommend just buying one of the pre-made ferrofluid toys online. (I saw some for ~$30). You will get a lot more ferrofluid for your money if you buy just the ferrofluid, however making the toy is a bit of work.

GOOD LUCK!

edit: no combinations of the following worked for me: acetic acid, hydrogen peroxide, pep plastic.

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I don't have a full answer, but a hint at how to choose your liquid. You want the ferrofluid not to mix with it, so your fluid has to be immiscible with the ferrofluid solvent (or carrier fluid; ferrofluids are colloidal suspensions). In the case of your “FerroFluid EFH-1”, the solvent is a light mineral oil, so you should go with a polar solvent.

Secondly, you want the ferrofluid solvent not to touch the glass, to avoid staining. In order to do so, you need your liquid to wet the bottle more than the mineral oil, i.e. to have a smaller contact angle. You can play on both the bottle material and nature of the fluid to achieve this. I suggest protic polar solvents, which should wet regular glass well: water, ethanol, isopropanol, acetic acid, …

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  • $\begingroup$ Hey thanks a lot for all this, it will really help in the search for the right one. I will narrow down the list of all clear liquids i can find with these filters you gave me and see for each how it goes. So far even alchohol didnt prevent it 100%, the only 100% that i've seen is hydrogen peroxide (tried it few hours ago) - though the ferrofluid acts weird.. completely different than in alchohol :) $\endgroup$
    – Damjan Stankovic
    May 18, 2012 at 3:25
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    $\begingroup$ @DamjanStankovic I know I'm late to the party, but just wondering what was your final solution? $\endgroup$
    – Drejc
    Jun 24, 2019 at 7:55
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No biggie. For aqueous ferrofluid, silanize the glass with Rain-X automotive windshield treatment. If you want both a hydrophobic and oleophobic glass surface, fluoroalkylsilane surface coupling

http://www.gelest.com/gelest/forms/GeneralPages/Applications/hydrophobic_materials.aspx

GLASSCLAD 18
AQUAPHILE AQ
AQUAPHOBE CF
AQUAPHOBE CM

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What about an ammonia-based fluid mix? I saw one guy on youtube that said he made it with Windex (the liquid was a clear greenish color) and another guy said he made it with Windolene(he's in the UK) but it went cloudy after a while. Meanwhile doing some other research I found someone who says their product (they sell ferrofluid desk toys) should be kept at room temp and will go cloudy if kept too cold. My guess is the guy in the UK had it accidentally get too cold.. because it's the UK, lol.

Those are my ideas, hope they help. :)

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    $\begingroup$ Do you have the links to the "guy on youtube"? It's always helpful to have answers that are supported by references, giving the OP additional information to address their question. $\endgroup$
    – bobthechemist
    Dec 8, 2013 at 1:59

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