# Shampoo, anyone? **URL:** \ **Category:** Factual Questions\ **Created:** [December 8, 2000, 7:24am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596 "2000-12-08T07:24:34Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![van](https://avatars.discourse-cdn.com/v4/letter/v/13edae/32.png) [@van](https://boards.straightdope.com/u/van)\ **Post date:** [December 8, 2000, 7:24am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/1 "2000-12-08T07:24:34Z")
I’ve noticed that when shampoo (or honey) is poured into the palm or onto some surface, the normally straight column of falling liquid suddenly breaks into contortions and squiggles at the end. Why does this happen? And why doesn’t it seem to happen with other viscous liquids like motor oil? Anyone with expertise in computational fluid dynamics care to help? ---
**Author:** ![Geek\_Mecha](https://avatars.discourse-cdn.com/v4/letter/g/ecae2f/32.png) [@Geek\_Mecha](https://boards.straightdope.com/u/Geek_Mecha)\ **Post date:** [December 8, 2000, 8:23am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/2 "2000-12-08T08:23:42Z")
I think it depends more on how you pour it out rather than what you’re pouring. You probably need a slow, steady trickle. I can get my Elmer’s glue to squiggle, and based on what I’ve seen on HGTV, paint, varnish, and epoxy all squiggle, too. ---
**Author:** ![van](https://avatars.discourse-cdn.com/v4/letter/v/13edae/32.png) [@van](https://boards.straightdope.com/u/van)\ **Post date:** [December 8, 2000, 9:12am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/3 "2000-12-08T09:12:32Z")
I’m not so sure about whether it’s the WAY you pour or WHAT you pour. What I would like to know is WHY it happens. If I pour with a slow, steady trickle, the squiggles intensify and really whip around at the bottom. Also, the height of pouring seems to increase the effect. Getting the stuff back INTO the bottle after the experimentation is no fun at all though! ---
**Author:** ![Geek\_Mecha](https://avatars.discourse-cdn.com/v4/letter/g/ecae2f/32.png) [@Geek\_Mecha](https://boards.straightdope.com/u/Geek_Mecha)\ **Post date:** [December 8, 2000, 10:06am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/4 "2000-12-08T10:06:52Z")
Not a problem with the epoxy. 🙂 Okay, okay, I’ll let the people who know what they’re talking about take over now. ---
**Author:** ![Gaspode](https://avatars.discourse-cdn.com/v4/letter/g/aeb1de/32.png) [@Gaspode](https://boards.straightdope.com/u/Gaspode)\ **Post date:** [December 8, 2000, 10:41am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/5 "2000-12-08T10:41:34Z")
The way it was explained to me was like this. The liquid hitting your hand stops nearly dead. This causes the next bit to stop and so on sending a shockwave up the moving column of liquid. If you turn your tap (faucet?) on real gently and run water into a half-filled sink (basin?) and it isn’t aerated you can often see the tiny rings around the bottom of the stream. With more viscous liquids if the column moves even a tiny bit off to one side, or the pool at the bottom is asymmetrical then the shockwave moves more to the opposite side, causing the column to move as well. This is where it gets tricky. These liquids are sheer thickening (ie they get thicker when you apply pressure to them like silly putty). As the column gets more and more off-centre relative to the hole in bottle the outside edge has to move faster than the inside because it has to travel further. The faster it travels the thicker it becomes and the slower it is able to travel, bringing the column back around. Of course the shockwave is still pushing it outwards so it wanders all over the place depending on how fast the liquid is flowing and how powerful the shockwaves. I have absolutely no idea if this I true, but I was told by a fysisi, a phisic, a phyci, a really smart bloke who knew about these things. ---
**Author:** ![AxeElf](https://avatars.discourse-cdn.com/v4/letter/a/e99b99/32.png) [@AxeElf](https://boards.straightdope.com/u/AxeElf)\ **Post date:** [December 8, 2000, 11:50am UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/6 "2000-12-08T11:50:35Z")
I wonder if it works with real poo, too. ---
**Author:** ![Gaspode](https://avatars.discourse-cdn.com/v4/letter/g/aeb1de/32.png) [@Gaspode](https://boards.straightdope.com/u/Gaspode)\ **Post date:** [December 8, 2000, 12:35pm UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/7 "2000-12-08T12:35:57Z")
> [@](#): > > \*Originally posted by AxeElf \* > \*\*I wonder if it works with real poo, too. > \*\* Only if you’ve been chowing down on your favourite prune juice and laxette daiquiri again. And a great big, warm, friendly welcome to the SDMB AxeElf. ---
**Author:** ![van](https://avatars.discourse-cdn.com/v4/letter/v/13edae/32.png) [@van](https://boards.straightdope.com/u/van)\ **Post date:** [December 8, 2000, 12:43pm UTC](https://boards.straightdope.com/t/shampoo-anyone/44596/8 "2000-12-08T12:43:12Z")
P-h-y-s-i-c-i-s-t. Yeah, that sounds like the right explanation. Damn, I wish I’d thought of that 😉 > [@](#): > > \*Originally posted by Gaspode \* > \*\*The way it was explained to me was like this. The liquid hitting your hand stops nearly dead. This causes the next bit to stop and so on sending a shockwave up the moving column of liquid. If you turn your tap (faucet?) on real gently and run water into a half-filled sink (basin?) and it isn’t aerated you can often see the tiny rings around the bottom of the stream. With more viscous liquids if the column moves even a tiny bit off to one side, or the pool at the bottom is asymmetrical then the shockwave moves more to the opposite side, causing the column to move as well. This is where it gets tricky. These liquids are sheer thickening (ie they get thicker when you apply pressure to them like silly putty). As the column gets more and more off-centre relative to the hole in bottle the outside edge has to move faster than the inside because it has to travel further. The faster it travels the thicker it becomes and the slower it is able to travel, bringing the column back around. Of course the shockwave is still pushing it outwards so it wanders all over the place depending on how fast the liquid is flowing and how powerful the shockwaves. I have absolutely no idea if this I true, but I was told by a fysisi, a phisic, a phyci, a really smart bloke who knew about these things. \*\*