Oobleck, a mixture of cornstarch and water, behaves as a non-Newtonian fluid. Its viscosity changes depending on the force applied: it flows like a liquid when poured slowly, but stiffens like a solid under sudden pressure. This unique behavior leads to questions about its stability, and Oobleck can dry out.
The Drying Process
When Oobleck is left exposed to air, the water within the mixture gradually evaporates, similar to how a puddle disappears. As water turns into vapor and leaves, the cornstarch particles, suspended in the water, are left behind.
Dried Oobleck’s appearance varies with its initial thickness and drying conditions. It might transform into a brittle, solid mass or a crumbly, powdery residue. Once dry, the cornstarch particles are no longer surrounded by water, and the mixture loses its characteristic non-Newtonian behavior, becoming a simple powder or a hard clump.
Reversing the Drying
Dried Oobleck can be rehydrated and brought back to its original state. To reactivate it, gradually add water to the dried cornstarch residue. Begin by adding small amounts of water and mixing thoroughly, ideally with your hands, to ensure even distribution.
Continue adding water slowly, mixing until the cornstarch absorbs the liquid and the mixture regains its non-Newtonian consistency. Adding water too quickly can dilute it, so a gradual approach is best. This process suspends the cornstarch particles in water, restoring Oobleck’s unique properties.
The Science Behind Oobleck’s Behavior
Oobleck’s unusual behavior stems from its composition: it is a suspension of cornstarch particles in water. Unlike a solution where a substance dissolves completely, cornstarch particles do not dissolve; instead, they remain dispersed throughout the liquid. These particles are tiny, typically 1 to 10 microns in size.
When undisturbed or under slow forces, water lubricates the cornstarch particles, allowing the mixture to flow like a liquid. Under sudden, strong force, particles are pushed together, jamming to form a rigid structure that resists the force, making Oobleck feel solid. When the force is removed, particles move freely, and Oobleck returns to its liquid-like state. Drying removes the water, which is the medium for this suspension, leaving solid cornstarch. Rehydrating reintroduces water, suspending the particles again and restoring their unique shear-thickening properties.