# Silly Putty as body armor **URL:** \ **Category:** Factual Questions\ **Created:** [June 27, 2006, 5:55pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366 "2006-06-27T17:55:17Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Belrix](https://avatars.discourse-cdn.com/v4/letter/b/ed655f/32.png) [@Belrix](https://boards.straightdope.com/u/Belrix)\ **Post date:** [June 27, 2006, 5:55pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/1 "2006-06-27T17:55:17Z")
Silly putty is wierd stuff. Push slowly and it deforms, whack it with a hammer and it shatters. There’s probably a good technical term for this but in general, it’s fun, wierd, stuff. A cop friend has a body armor vest with steel plates in it, it’s bulky and doesn’t move well. (They make him buy it himself, too - it’s not issued. Cheap bastards!) I was thinking that there should be some cool silly-putty-like material that a vest could be made with- under normal movement it should flex and move but hit quickly it should be stiff. Anything out there like this? ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [June 27, 2006, 6:06pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/2 "2006-06-27T18:06:14Z")
You bet there’s stuff like that out there! [Liquid Armor](http://www.sciencentral.com/articles/view.php3?type=article&article_id=218392807) > [@](#): > > The liquid - called shear thickening fluid is actually a mixture of hard nanoparticles and nonevaporating liquid. It flows normally under low-energy conditions, but when agitated or hit with an impact it stiffens and behaves like a solid. This temporary stiffening occurs less than a millisecond after impact, and is caused by the nanoparticles forming tiny clusters inside the fluid. “The particles jam up forming a log jam structure that prevents things from penetrating through them,” Video: [Liquid armor](http://video.google.com/videoplay?docid=5469322483836077126&q=liquid+armor) ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 27, 2006, 6:08pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/3 "2006-06-27T18:08:11Z")
> [@Belrix](#): > > There’s probably a good technical term for this… Viscoelastic. > [@Belrix](#): > > Anything out there like this? [Yep](http://www.freepatentsonline.com/5738925.html). I don’t know if it’s of practical use yet. ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [June 27, 2006, 6:22pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/4 "2006-06-27T18:22:55Z")
> [@Belrix](#): > > There’s probably a good technical term for this but in general, it’s fun, wierd, stuff. > [@Q.E.D.](#): > > Viscoelastic Actually, I think [Non-Newtonian fluid](http://en.wikipedia.org/wiki/Non-Newtonian_fluid) is a better descriptor. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [June 27, 2006, 6:24pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/5 "2006-06-27T18:24:27Z")
_Thixotropy_ is the term you’re looking for. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 27, 2006, 6:36pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/6 "2006-06-27T18:36:12Z")
> [@CalMeacham](#): > > _Thixotropy_ is the term you’re looking for. That’s the opposite of what Silly Putty does, though. A thixotropic material is stiff when let to stand, but thins out when agitated or stirred. Silly putty is semi-solid, normally, but gets stiffer when struck. > [@CynicalGabe\[/quote](#): > > Actually, I think Non-Newtonian fluid is a better descriptor. Non-Newtonian fluid describes a wide range of materials with properties ranging from viscoelastic to thixotropic. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [June 27, 2006, 6:53pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/7 "2006-06-27T18:53:20Z")
> [@](#): > > That’s the opposite of what Silly Putty does, though. A thixotropic material is stiff when let to stand, but thins out when agitated or stirred. Silly putty is semi-solid, normally, but gets stiffer when struck. Not true. Silly putty _is_ stiff when it stands – it flows slowly with time to fill that egg container, but it’s a slow flow. When worked _slowly_ silly putty thins out (it’s only when struck rapidly that it shatters). A lot of paints are thixotropic – they spread when you work them slowly with a brush, but gel when standing. The refeerences in Jearl Walker’s **Flying Circyus of Physics** call Silly Putty thixotropic. ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [June 27, 2006, 6:55pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/8 "2006-06-27T18:55:53Z")
It’s a [Dilatant](http://en.wikipedia.org/wiki/Dilatant) material. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [June 27, 2006, 7:03pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/9 "2006-06-27T19:03:06Z")
It’s a practical application for [oobleck!](http://sciconn.mcb.arizona.edu/oobleck/oobleck.html) ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [June 27, 2006, 7:03pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/10 "2006-06-27T19:03:53Z")
> [@galt](#): > > It’s a [Dilatant](http://en.wikipedia.org/wiki/Dilatant) material. Well, if **Cal** is right about the material thinning out when worked _slowly_, and I’ve no reason to doubt that he is, then that’s not quite right, either. It seems to have properties of several different classes of materials, and not really belonging to any one of them. In that case, **Gabe** ’s “Non-Newtonian fluid” is probably about the most accurate classification, after all. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [June 27, 2006, 7:06pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/11 "2006-06-27T19:06:04Z")
> [@](#): > > In that case, Gabe’s “Non-Newtonian fluid” is probably about the most accurate classification, after all. Could be. Silly Putty is weird stuff, any way you look at it. I’m so dense that it was _years_ before I realized that “Silly” Putty was probably inspired by "sili-"cone putty. ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [June 27, 2006, 7:09pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/12 "2006-06-27T19:09:47Z")
I’m not sure it’s correct to say it “thins out” when worked slowly. It flows/deforms slowly, like an extremely thick liquid. If you attempt to deform it too quickly, it breaks sharply. I have a hunk of it right here if you want me to perform any experiments. 😃 ---
**Author:** ![Belrix](https://avatars.discourse-cdn.com/v4/letter/b/ed655f/32.png) [@Belrix](https://boards.straightdope.com/u/Belrix)\ **Post date:** [June 27, 2006, 7:13pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/13 "2006-06-27T19:13:26Z")
> [@CalMeacham](#): > > Could be. Silly Putty is weird stuff, any way you look at it. > > I’m so dense that it was _years_ before I realized that “Silly” Putty was probably inspired by "sili-"cone putty. :smack: …and I never made the connection until right now! (not that I really \*made \*a connection as had it made \*for \*me.) ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [June 27, 2006, 7:19pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/14 "2006-06-27T19:19:05Z")
Wow, more Larry Niven stuff come to life. This sounds exactly like the “impact armor” he had Louis Wu wearing in the _Ringworld_ sequels – ordinarily it was pretty soft and flexible, but if something like a bullet hit it, it would go instantly rigid and protect the user. ---
**Author:** ![BMalion](https://avatars.discourse-cdn.com/v4/letter/b/e274bd/32.png) [@BMalion](https://boards.straightdope.com/u/BMalion)\ **Post date:** [June 27, 2006, 7:20pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/15 "2006-06-27T19:20:21Z")
so it’s a Viscoelastic, non-newtonian, thixotropic, dilatantic, oobleckian substance, right? ---
**Author:** ![Raguleader](https://avatars.discourse-cdn.com/v4/letter/r/258eb7/32.png) [@Raguleader](https://boards.straightdope.com/u/Raguleader)\ **Post date:** [June 27, 2006, 9:12pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/16 "2006-06-27T21:12:18Z")
What properties does it possessed when placed on a treadmill? _ducks and flees_ But seriously, does anybody have a sizable quantity of silly putty and a gun that we could use for experimenting? Even if it doesn’t work, it should be entertaining. ---
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [June 27, 2006, 11:00pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/17 "2006-06-27T23:00:56Z")
> [@Raguleader](#): > > But seriously, does anybody have a sizable quantity of silly putty and a gun that we could use for experimenting? Even if it doesn’t work, it should be entertaining. E-mail _Mythbusters_. Now. Now!!! ---
**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\ **Post date:** [June 27, 2006, 11:16pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/18 "2006-06-27T23:16:57Z")
> [@BMalion](#): > > so it’s a Viscoelastic, non-newtonian, thixotropic, dilatantic, oobleckian substance, right? No, it’s a soquid. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [June 27, 2006, 11:37pm UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/19 "2006-06-27T23:37:41Z")
> [@HeyHomie](#): > > E-mail _Mythbusters_. Now. My thought exactly. Q.E.D., paging Q.E.D! ---
**Author:** ![MaryEFoo](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@MaryEFoo](https://boards.straightdope.com/u/MaryEFoo)\ **Post date:** [June 28, 2006, 12:35am UTC](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366/20 "2006-06-28T00:35:35Z")
**Squink** ’s cite: "but when agitated or hit with an impact it stiffens and behaves like a solid. This temporary stiffening occurs less than a millisecond after impact, " How far does a pistol bullet travel in a millisecond? [Next page](https://boards.straightdope.com/t/silly-putty-as-body-armor/362366.md?page=2)