Walkin' on Oobleck Oobleck is a mixture of cornstarch and water in the ratio of about 1.5:1. It's the classic non-Newtonian fluid demo. Mix up a batch and pour onto a plate or pan. Then ask someone, preferably your local TV talent wearing a nice dark blue suit, to slap their hand down on the mix. It just sits there without splashing. Recently it's become the rage to mix up huge quantities of this stuff, pour it into a pool and have people run over the top. If you stop, you sink into the mix, but if you keep moving you're OK. One of the many videos on youtube is linked in the story below. The big question is, if you want to do this what do you need to make it happen?
I've walked across a tub of this stuff at an orientation event at Bowling Green University in 2007. The most interesting thing was not the running over the top of the liquid, but rather what happened when you stopped. Of course you sink, if feels a bit weird on your feet and calves, but getting out was the weird part. After sitting down on the edge of the tub I tried to pull both feet out. It didn't happen. You can't pull both out at the same time!
I'm pretty sure that they used the 1.5:1 ratio for their mixture. You can't really tell from the photo but there was a scaffolding platform built up around the tub of oobleck. A cement mixer was used to prepare the oobleck but I did not see how they poured it into the tub. Volunteers were on hand with canoe paddles to complete the mixing during the event. Over time the mixture seemed to separate a bit and some additional mixing was needed.
The top surface of the platform was covered with interlocking rubber tiles like you see in gym's. This gave the top a nice walking surface since everyone took off their shoes and socks to walk on the oobleck. This was only a one day event so I'm sure that sanitary issues were not a huge concern. I do have to wonder how you could do this over say a weekend event and keep it clean as well as well mixed.
