This ‘silly’ toy made its debut this week in 1950 at the International Toy Fair in New York City.
It stretches without breaking, but can be “snapped off” cleanly. It bounces higher than a rubber ball, with a rebound of 80%. If you hit it with a hammer, it keeps its shape, but pushing it with light, even pressure flattens it easily. The manufacturer– Binney & Smith of Easton, Pa.–likes to call Silly Putty a “real solid liquid.”
In more technical terms, Silly Putty is a dilatant compound, which means it has an inverse thixotropy–that is, as a viscous suspension or gel, it becomes solid under the influence of pressure. Another chemical dictionary tells me that the term “dilatancy” is used in rheology to “identify the flow property of certain suspensions in which the resistance to flow increases at a greater rate than the increase in the rate of flow.” The material, Binney & Smith says, has “been the subject of dissertations by aspiring physicists and chemists.”
The first Silly Putty was made by mixing silicone oil with boric acid. The formula and manufacturing process have remained essentially unchanged for 50 years–except for added colorants to make the newer bright, glow-in-the-dark, temperature-changeable, or 50th-anniversary gold putty. More than 4,500 tons, or 300 million eggs, have been sold since 1950.
James Wright, a researcher at General Electric’s New Haven, Conn., laboratory, discovered the material in 1943 in an attempt to make synthetic rubber during World War II. A practical use for the putty couldn’t be found, so it was finally sold as a novelty item in 1949 in a local toy store.
Visit “What’s That Stuff” to continue reading about Silly Putty.
Excerpted with permission, Chemical & Engineering News
Copyright © 2000 American Chemical Society