Those of you who were traumatised at the sight of our floury moon craters should look away now ...
Last week was the Science Festival in Cambridge, an annual event packed with some imaginative and exciting activities for little and big people. Unfortunately mine were felled by colds so we couldn't quite face dragging into town and fighting the crowd; instead I remembered the fabulously weird properties of cornflour in water I'd seen described at PlanetScience (a brilliant resource for anyone wanting to make a lot of mess), and that Simmy had told me about a few posts back - so we laid out a mat and got on with it. I learned about colloidal solutions at school and university but I'd never seen it in action before.
Oh My Goodness.
Once we'd got the proportions right - the recommended 8 eggcups cornflour to 4 eggcups water was a bit thin - we could scoop it up and roll it into balls (solid phase)
then open up our hands and watch as it behaved like a liquid and ran through our fingers.
People, there was food colouring. There was flour all over the floor. There was a LOT of laughing, and we even had to save the flour bowl for Mr DC to play with when he got home.
We embedded eggcups in the goop and found that if we pulled them hard they would stick fast, but if we were more gentle the flour particles would not stick together and the cup could come free. Quicksand, anyone?
The finale was a viewing of the Brainiac Walking on Custard clip which explains it far better than I have just done!