Silly Putty

Silly Putty is a toy based on silicone polymers that have unusual physical properties. It bounces, but it breaks when given a sharp blow, and it can also flow like a liquid. It contains a viscoelastic liquid silicone, a type of non-Newtonian fluid, which makes it act as a viscous liquid over a long time period but as an elastic solid over a short time period. It was originally created during research into potential rubber substitutes for use by the United States in World War II.

The name Silly Putty is a trademark of Crayola LLC; the company's factory is based in Easton, Pennsylvania, USA. Other names are used to market similar substances from other manufacturers.

As a bouncing putty, Silly Putty is noted for its unusual characteristics: it bounces but breaks when given a sharp blow; it can also float in a liquid and will form a puddle given enough time. Silly Putty and most other retail putty products have viscoelastic agents added to reduce the flow and enable the putty to hold its shape.

The original coral-colored Silly Putty is composed of 65% dimethylsiloxane (hydroxy-terminated polymers with boric acid), 17% silica (crystalline quartz), 9% Thixatrol ST (castor oil derivative), 4% polydimethylsiloxane, 1% decamethyl cyclopentasiloxane, 1% glycerine, and 1% titanium dioxide.

Silly Putty's unusual flow characteristics are due to the ingredient polydimethylsiloxane (PDMS), a viscoelastic substance. Viscoelasticity is a type of non-Newtonian flow, characterizing material that acts as a viscous liquid over a long time period but as an elastic solid over a short time period. Because its apparent viscosity increases directly with respect to the amount of force applied, Silly Putty can be characterized as a dilatant fluid.

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