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Homemade Ferrofluid

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LAN_403

Part Scavenger

Thu Apr 06 2006, 10:44AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

No, no time again, I've had some papers due this week and someother big stuff going on. I don't have a spare hour and a half.

I'll try to get back to it soon. I didn't get to try it sunday like I thought.

cbfull

Fri Apr 07 2006, 12:31PM

Registered Member #187 Joined: Thu Feb 16 2006, 02:54PM
Location: Central Ohio
Posts: 140

Has anyone tried the procedure that uses tetramethylammonium hydroxide as the surfactant? This formulation pops up more frequently than the oleic acid/NH4OH when I do a search on google.

I am planning to test this formulation when I get the chance because I have all the materials. Here is the most descriptive link I could find:

I'm hoping it won't be too hard to make a decent amount of the stuff, I plan to practice with small batches first.

Heiders

Sun Apr 09 2006, 04:54AM

Registered Member #268 Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48

Ah ha! Thank you for that link, somewhere in it it mentions how susceptible to air oxidation the FeCl2 solution is. That is probably my problem, and having made a fresh solution, things should go well for a week or so. After then, it will most likely oxidize.

I have a wine evacuator

, which is a rubber stopper that fits in the top of a wine bottle and has a hand pump to suck out the air. Supposedly makes an opened bottle taste better the day after. Do you think that it would be capable to sucking out enough air to increase the usable life of my solution?

Carbon_Rod

Mon Apr 10 2006, 07:36AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

My yield was pretty bad using my own method. However, the nylon stopper on the test tube has worked fairly well for storing the stuff (most of the remaining oxides seem settle out over time.)

Self Defenestrate

Mon Apr 10 2006, 01:43PM

Registered Member #87 Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191

As soon as I get some more ferric chloride I'll give it a shot as well.

GreySoul

Sat Feb 24 2007, 12:41AM

Registered Member #546 Joined: Fri Feb 23 2007, 11:43PM
Location: Albuquerque, NM
Posts: 239

Hi all, first time poster, short term lurker :)

I was refered to you all from Andrew and I think I hit the jackpot for my ferrofluid.

So I made my first 2 batches with about the same success as everyone else here - lumpy blob with no spikes....and then I had success after much experiementing and figured I'd share what I found...

The FeCl3 I use is from Datek and has no adulterants, so the water solution step was bypassed resulting in a more concentrated ferrous chloride, I don't know if that made a huge differnce but it might have. Next up I used a vacum filter and erlynmyer flask to clean up the crud from the steel wool.

After that I was having the same trouble with getting a murky red crud instead of clean magnetite. Adding more ammonia solution certainly helped out. Careful titeration is best because too much ammonia seems to interfere with the oleic acid. At the very least it takes longer to cook it all off. I am using yellow lemon scented ammonia with soaps and surficants added, but not too worried. I noticed the lemon scent, color, and at least some soap comes out in the water.

My first try was with olive oil, and I quickly gave up on that. I got some oleic acid from the chemeistyrystore website as noted above. It was around $40/g delivered. A gallon should make > 100 gallons of ferrofluid, so I'll probably use some to make silly putty as well.

Anyways everything here is great so far, but then I got to the kerosene bit and decided to play around. I added a LOT of kerosene to one batch, about double what Andrew has on his site, and let it sit over night in my garage. The next day I had some very promising results after pouring off the non-magnetic but darkly stained excess kerosene. Tiny spikes form around a fairly weak ring magnet salvaged from a speaker.

But it wasn't spectacular.

So I started to experiment with differnt solvents. I've found that Zippo lighter fluid works the best, but quickly evaporates so your solution has to stay sealed. Goof Off (Xylol and Tolulene I think?) also works well but is considererably more toxic than kerosene or lighter fluid (which smells like kerosene but it works better...)

I tried to suspend the oleic acid in water but no amount of boiling or time seems to make a decent fluid.

Acetone works great to clean up spills, but is a crummy carrier fluid.

Liguid butane also works great for the 30 seonds or so you have before it boils off at STP.

So after all that I've settled on lighter fluid and charcoal starter fluid (same stuff?) as the best carrier for good spikes. Right now I am getting inch long spikes to form in the bottom of a pyrex cooking dish from a weak permanent magnet and when I bring a strong electromagnet near the container I get dancing spikes :)

One other thing I experianced.... I get 3 layers in my cylinder when I do this. A brown solvent layer on top, that shows no magnetism at all, a yellowish brown water layer, and a bottom layer that is the ferro-fluid, yet in the sites I have seen it says the ferrofluid should be the fluid that is suspended in kerosene at the top of the column.... any ideas? it sure makes it easy to get the fluid out since i can just stick a magnet to the bottom of my cylider and pour the rest off, but shouldn't I get some other results?

-Doug

p.s. sorry for raising a dead article, I just noticed the last post date... but hey... I'm new :) I'll post pics when I get some. Maybe tonight?

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