Cornstarch play

As you probably know, my husband is a Drilling Engineer. So, it is only natural to put something on my blog about drilling fluids...
In Drilling Fluid: The Lifeblood of the Well you can read about Visplex*, a substance used in the drilling fluid that transports cuttings from the bottom of a borehole to the surface. Visplex has the unusual property of being able to change form. When it is at rest it is a gel. When it is in motion it becomes a free-flowing liquid. A mixture of cornstarch and water also changes viscosity depending on whether or not it is agitated, but in a different way. When it is under pressure, it becomes a solid.
The other day, we spent the entire afternoon playing with the properties of this mixture. Carson loved to ooz his hand slowly into the liquid and then try to pull it out quickly only to have it trapped.