Watch what happens when you touch magnetized ferrofluid


Originally published at:


Call me unimpressed. I was looking for something closer to the scene in the Matrix where Neo’s hand turns to liquid metal.


As the supermagnet was brought to the ferrofluid, the spikes seemed to form in a geometric pattern, like a crystal: first one, then a central spike surrounded by six, usw. Is there any explanation for this phenomenon? Might it be useful for modeling crystal structure, or perhaps quantum phenomena, such as a Bose–Einstein condensate (



Please add Prometheus reference here.


I’ve not watched the video, so I hope I don’t duplicate too much of what is said there. Ferrofluid is amazingly versatile stuff. Beyond some occasional public references from speaker manufacturers and showing up in novelty vials as magnetic field demonstrators, it isn’t all that well known to the public.

One of its most prominent early uses (by the company Ferrofluidics, which brought it to market) was as a bearing seal for the spindles in hard disk drives. It has great viscosity (multiple formulations available), but because the viscosity can be altered by the application of magnetic field(s), it can be activated selectively to both block out foreign contaminants and to prevent it from being flung out of the bearing assembly under high rotational speeds. It revolutionized the industrial hard drive market in the late 70s and early 80s, and drives using ferrofluid were utilized in harsh military environments and even on the space shuttles. Of course, high-precision bearings are all over the place in industrial applications, and ferrofluid shows up in all sorts of applications involving rotating hubs, shafts, and spindles.

Another common application is speed control. Apply a magnetic field to a ferrofluid bearing and you can do everything a mechanical brake can do, but with reduced heat build-up/improved heat dissipation. A much higher degree of precision in control can be had with ferrofluid vs conventional mechanical means, which is an added benefit. Speakers (specifically tweeters) use it in essentially this application… as a damping medium that responds to excess energy and self regulates to prevent overheating and tear-up.

Ferrofluid is largely taken for granted today, but it made a large contribution to modern life and it continues to do so. And, as the summary indicates, it stains like crazy (there are solvents to get it mostly off of your skin, get it on your clothes and it’s not coming out!). Fascinating stuff, I’m glad to see it mentioned here! It’s something of which every erudite mutant should have knowledge, in my humble nerd-like opinion.


It really, really stains.

closed #8

This topic was automatically closed after 5 days. New replies are no longer allowed.