Cornstarch shapes clay with precision

NYU (US) — A new method to shape solid materials—in this case, modeling clay—uses cornstarch as its main ingredient.

Similar solutions have been effective in creating body armor—but for different reasons. The molecules in these fluids—also called shear-thickening fluids—are closely packed, but loosely arranged.

Under most conditions, they flow like most liquids. When met with pressure from an object or other force, its particles interlock and the fluid acts like a solid. Body armor comprised of shear-thickening fluids, when met with bullets, become hard and deflect incoming projectiles.

A research team from New York University sought to apply these principles in a different manner. Instead of using the solution to deflect objects, they aimed to use it as part of a process to shape a wall of modeling clay.

A variety of methods are used in manufacturing for shaping solid materials, ranging from laser cutting to high-speed jets of water. While altering the shape of such materials, such as glass, metal, or stone, is relatively straightforward, doing so with precision often proves challenging.

To shape the modeling clay, researchers submerged a motor-powered, plastic sphere through the cornstarch solution toward a containing wall made of modeling clay, stopping just short of the wall. Details are reported in the journal Physical Review of Letters.

Using the force of the sphere to harden the cornstarch solution, the researchers were able to make indentations in the wall of modeling clay. In addition, they were able to do so with a degree of precision by taking into account speed, force, and geometry.

By moving the sphere at fast speeds through the solution, they created large depressions in the clay; by slowing it down, they created smaller depressions.

The research was supported by grants from the National Science Foundation and the Department of Energy.

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