oobleck

Oobleck is a simple non-Newtonian fluid made from a mixture of cornstarch and water, often with a few drops of food coloring. A common recipe uses roughly two parts cornstarch to one part water by volume, but the exact ratio can vary and viscosity depends on temperature and concentration.

When stirred slowly, it behaves like a liquid; when struck quickly or subjected to a sudden force, it acts like a solid. This shear-thickening (dilatant) behavior occurs because the suspended starch particles form temporary networks that resist rapid movement, effectively trapping water and increasing resistance to flow.

The substance is typically prepared in kitchens and classrooms for demonstrations of rheology and materials science. It is non-toxic and edible when made with food-grade ingredients, though it can be messy and was not designed as a food product.

Origin and name: The term “oobleck” draws from Dr. Seuss’s Bartholomew and the Oobleck, published in 1949, in which a fictional substance by that name causes trouble. The demonstration using a cornstarch–water mixture predates the book, but the name was popularized by it and has become the common label for the mixture in educational contexts.

Applications and significance: Oobleck is widely used to illustrate non-Newtonian fluids, viscosity, and the concept of shear-dependent flow in classrooms and museums. While it has limited practical uses beyond demonstrations, it helps students and lay audiences understand how some materials change consistency under different forces.