Magnetism makes silly putty fun again

The image above is a screen capture from a video clip where the black ooze gobbles up that rare-earth magnet. It’s actually a blob of Silly Putty which was slightly altered to add magnetic properties. [Mikeasaurus] grabbed some ferric iron oxide powder from an art supply store and donned gloves and a dust mask while massaging it into the silicone polymer. If you get the right mix of the two materials you end up with a flowing substance that performs mysteriously when exposed to a magnetic field.

Check out the video after the break to see some of the tricks that [Mikeasaurus] can do. The putty really looks like it has a life of its own. It will stretch a remarkable distance to get close to the magnets (amorphous stretch). If left in contact with one it will fully engulf it and then form an orb.

Now, is there any way to use this with electromagnetic fields to build a morphing robot?


  1. brad says:

    first thought: i need to go buy silly putty and iron filings right now.

    second thought: does this remind anyone of the evil blob from fern gully?

  2. pollopants says:

    This is basically just making your own smart mass:

  3. Digital Ruse says:

    Or, head on over to ThinkGeek and get some:

  4. Pete says:

    Does anyone else have a pet peeve about the phrase “defy gravity”? It really grinds my gears.

  5. _gl.tch says:

    interesting effect, it reminds me of watching white blood cells engulf foreign bodies.

    I always wondered how the cells did it and now I know, f-ing magnets!

  6. Velli says:

    Nah, you can defy gravity all you want, but no matter your attitude, it’s still gonna drag you down.

    Silly putty has to be slightly less messy than ferrofluid.

  7. BigM says:

    Self healing polymer covering for robotic skeletons? Neat idea.

  8. Debraj says:

    Once devoured, how do you recover magnet? Say after one night?

  9. JJ says:

    I have some ferro fluid. I wonder if I can its soluble in silly putty

  10. @JJ Possible, ferrofluid is basically iron nanoparticles (IIRC 300-1500nm) in an oleic acid binder.
    They make it under specific conditions so that it doesen’t degrade when exposed to air.

    You can even use ferrofluid or a close analog to it as a seal for a vacuum pump.
    The magnetic field holds it in place and stays sealed over time despite the pressure difference.

    I’d also try the ebay iron powder (300um mesh) as this is pretty fine and ought to work in much the same way.. failed magnetic solder experiment.

  11. raidscsi says:

    @ Pete
    Does anyone else have a pet peeve about the phrase “grinds my gears”? You can’t actually grind gears in a transmission.

  12. Hirudinea says:

    Silly Putty, they ought to call is Awsome Putty!

  13. Pete says:

    I am not sure if people do or not.

  14. says:

    Does anyone else have a pet peeve about people telling other people their pet peeves? No? Just me? Thought so…

  15. Drake says:

    hmmm what if we added some aluminum dust and a bit of magnesium sounds like a plastic thermite!!!!!!!

  16. Jess says:

    Oh No!!!! Attack of the Killer Black Olive!!!! Run for your lives!!!!!!

  17. Decius says:


    No one watches that, this won’t stop your tree cutting machine D:

  18. ENKI-][ says:

    Wait… When did Silly Putty stop being fun? Why wasn’t I told?

  19. Whatnot says:

    defy verb (defies, defying, defied)
    1 openly resist or refuse to obey.

    So you can say ‘defy gravity’ really, defeating it is another thing.

  20. Chris says:


    No, but it did remind me of the black blob that engulfed Tasha Yar.

  21. Hunty says:

    I think anyone who replies to a hackaday post with “you can buy that pre-made here” doesn’t understand the point of hackaday. :)

  22. matt says:

    @raidscsi You can actually grind gears in a transmission. You see they actually used to make transmissions that you had to shift manually, now I don’t mean from park to drive I mean from first to second and so on and so fourth while your driving down the road and there was this third pedal all the way on the left that you had to step on to disengage the engine from the transmission before switching gears it’s called the clutch. So as it turns out if you have a car with a standard transmission its easy to grind your gears all you have to do is let off the clutch with the gear partially engaged and you get to hear the most painful noise you will ever hear your transmission make.

  23. tehgringe says:

    Magnets, Fucking miracles!

  24. Kuhltwo says:

    anyone besides me thinking of T2?

    I like the idea of silly putty thermite, wonder if it’ll work.

  25. Chris says:

    Funny to see this the day after I learned you’re not supposed to glue supermagnets with JB Weld (steel-bearing epoxy), because it will spread to cover the magnet. Which is (usually) not what you intended.

  26. silvesterstillalone says:

    @matt. lulz. i was waiting for it.

    this video seems sped up. i wondwer how the material could be made to move faster. it looks like it is already saturated. furthermore has anyone seen magnetized particles suspended in a solution like this?

  27. percy j says:

    Phyrexian oil

  28. Frogz says:

    anyone remember gak from the 90s?
    they had all kinda
    glow in the dark gak
    a whole rainbow of colors
    gak with styrofoam balls
    and yes, even magnetic gak
    i found the little container of it years later, it became a black paste that could stain ANYTHING

    btw, people, dont forget my “dirt cheap ferrofluid”
    just add some printer toner(the magnetic type) and see what happens :D

  29. Pogyhauler says:

    Can’t grind gears????

    He said that?

    Either He’s real, real, young.
    Or I’m real, real old.

    I thought syncromesh was the dawn of a new age….

  30. ‘ferric iron oxide’ – seriously, HaD?
    ferric means iron-containing or iron(III).
    Iron(III) oxide, also known as ferric oxide, is probably what you were aiming for.
    Same stuff you use in thermite.


  31. Grod says:

    @matt – “the most painful noise you will ever hear your transmission make” is not that of grinding gears but the kind of THUMP SSsccccrraaaaaaappppeee kerCHUNK noise as it falls off. Far more painful, both psychologically and financially.

  32. zedbob says:

    was in my friend’s trans am when he dropped his tranny. he had a speed shifter and down-shifted from 5th to reverse when he missed 4th gear!! Nastiest sounds I ever heard a car make followed by the nastiest sounds I ever heard him make.

    • svengali says:

      How strange, every manual transmission car i have driven has been specifically designed so that if reverse is directly under the top gear you cannot physically shift from that gear straight down to reverse for this reason. Though i have seen cars with very worn gearboxes that you were able to do this on.

  33. lstg says:

    You can get similar magnetic putty as well as other weird types of putty (transparent, heat sensitive) at

  34. gt says:

    it’s a miracle. how do magnets work?

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