Silly Putty (originally called Nutty Putty, and also marketing by other companies as Thinking Putty, Bouncing Putty) is the Crayola owned trademark name for a class of silicone plastics known as Bouncing Putty. It is marketed today as a toy for children, but was originally created by accident during research into potential rubber substitutes for use by the United States in World War II.
It was after its success as a toy that other uses were found. The material's unique properties have found niche use in medical and scientific applications. It is used in large quantity by physical therapists for rehabilitative therapy of hand injuries. A number of other brands have emerged which alter the material's properties offering different levels of resistance for this market. Power Putty and TheraPutty are examples. The material is also used therapeutically for stress reduction. Patients with ADD, ADHD, Fragile-X and many other disorders find its continuous tactile sensation to be calming and focusing. In the home it can be used to pick up dirt, lint and pet hair, and it was even used by Apollo astronauts to secure their tools in zero-gravity.
The original coral-colored Silly Putty is composed of 65% dimethyl siloxane (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 liquid. 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.
Silly Putty is also a fairly good adhesive. When newspaper ink was petroleum based, Silly Putty could be used to transfer newspaper images to other surfaces, possibly after introducing distortion. Newer papers with soy-based inks are more resistant to this activity.
Silly Putty will dissolve when in contact with an alcohol. After the alcohol evaporates, the material will not exhibit the original properties.
It is advised not to submerge Silly Putty in warm or hot water, as it will become softer, and thus "melt" much faster, and it also is harder to remove small amounts of it from surfaces. After a long period of time, it will go back to its original viscosity.
Silly Putty is sold as a 13 gram (0.47 ounce) piece of plastic clay inside an egg-shaped plastic container. It is available in various colors, including glow-in-the-dark and metallic. The brand is owned by Crayola LLC (formerly the Binney & Smith company), which also owns Crayola crayons. Today, twenty thousand eggs of Silly Putty are produced daily. Since 1950, more than 300 million eggs of Silly Putty have been sold, or approximately 4500 tons. Other Bouncing Putty brands offer the material in larger size containers and in a wide variety of colors.
Credit for the invention of Silly Putty is disputed and has been attributed to both Earl Warrick, of the then newly-formed Dow Corning, and James Wright, a Scottish inventor working for General Electric in New Haven, Connecticut. Throughout his life, Warrick insisted that he and his colleague, Rob Roy McGregor, received the patent for Silly Putty before Wright did, but Crayola's history of Silly Putty states that Wright first invented it in 1943. Both researchers independently discovered that reacting boric acid with silicone oil would produce a gooey, bouncy material with several unique properties. The non-toxic putty would bounce when dropped, could stretch farther than regular rubber, would not collect mold and had a very high melting temperature.
Wright found that the substance did not contain all the properties needed to replace rubber and so it spent several years languishing as a mere laboratory curiosity. In 1945, hoping there was a use for his new developed putty, Wright sent a sample to scientists all around the world, but no practical use was ever found. Finally, in 1949, the putty reached the owner of a toy store, Ruth Fallgatter, who contacted Peter Hodgson, a marketing consultant, to produce her catalog and discuss selling bouncing putty. The two decided to market the product by selling it in a clear case for $2. The putty proceeded to outsell every item in the catalogue except for 50 cent Crayola crayons. Despite the fortune it made, Fallgatter did not pursue it further, but Hodgson saw its potential.
Already $12,000 in debt, Hodgson borrowed $147 to buy a batch of the putty to pack one ounce portions into plastic eggs for $1, calling it Silly Putty. After making progress in the industry, even selling over 250,000 eggs of silly putty in three days, Hodgson was almost put out of business in 1951 by the Korean War. Silicone, a main ingredient in silly putty, was put on ration, harming his business. In 1952, a year later, the restriction on silicone was lifted and the production of Silly Putty was resumed. Initially, it was primarily targeted towards adults. However, by 1955 the majority of its consumers were aged 6 through 12. In 1957 Hodgson produced the first televised commercial for silly putty, which aired during the Howdy Doody Show.
Peter Hodgson died in 1976. A year later, Binney and Smith, the makers of Crayola products, acquired the rights to Silly Putty. By 1987, Silly Putty had pushed sales to over two million eggs annually.