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Silly Putty

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Silly putty dripping through a hole
Silly Putty shown as a solid cube

Silly Putty (originally called nutty putty, and also known as Potty Putty) is a silicone plastic, marketed today as a toy for children, but originally created as a fortuitous accident during the course of research into potential rubber substitutes for use by the United States during World War II. During World War II, the USA was looking for a synthetic rubber compound because of the difficulties in obtaining natural rubber from the Far East. In researching this problem, James Wright of General Electric reacted boric acid with silicone oil and produced a gooey material – though it bounced it was certainly not a rubber substitute. No uses for it were found until the 1950s when its potential as a toy was realised. It was after its success as a toy that other uses were found. It has found applications in medical and scientific simulations, and has also been used in stress-reduction and physical therapy. 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 tools in zero-gravity.

Description

Silly putty is an inorganic polymer, noted for its many unusual characteristics: It bounces, but breaks when given a sharp blow. Yet, it can flow like a liquid and will form a puddle given enough time.

Silly Putty is composed of 65% Dimethyl Siloxane (hydroxy-terminated polymers with boric acid), 17% Silica, quartz crystalline, 9% Thixotrol ST, 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. Silly Putty has sometimes been characterized as a dilatant fluid. However, according to the science of rheology, this is not strictly correct and it is more accurate to characterize it as a viscoelastic or thixotropic liquid.

Silly Putty is also a fairly good adhesive. When newspaper ink was easier to rub off, Silly Putty could be used to transfer newspaper images to other surfaces, possibly after introducing distortion. Newer papers are more resistant to this activity.

Silly Putty is sold as a 0.47 oz (13 g) 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 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.

Origins of Silly Putty

Silly Putty was invented in 1943 by Carson Spung of General Electric when he dropped boric acid into silicone oil. He was looking for a substitute for rubber. GE supplied the newly discovered dilatant compound to researchers around the world. None found a use for it, but they all loved playing with it.

In 1943, Dr. Madison Kocks left the Mellon Institute of Industrial Research to join the newly formed Dow Corning Corporation. His research was refocused: help the war effort by developing a synthetic rubber substitute. Although he failed to produce a suitable rubber before the end of the war, one result of his experiments was a silicone bouncing putty.

The product was then commercialized by MJ and Duke in 1949 after the marketing expert attended an informal "nutty putty" party where chemists were playing with the substance after hours. Renamed "Silly Putty" because of its main ingredient, silicone, the product was a smash hit.

Raw Silly Putty polymer is available as Dow Corning 3179 Dilatant Compound. There are recipes for homemade silly putty using Elmer's Glue and boric acid. These produce a compound which is similar in chemical structure but is different in the elements which form that structure.

Although Silly Putty is fundamentally the product of combining boric acid and silicone oil, one of the main ingredients in name-brand Silly Putty is elemental silicon (silicon binds to the silicone and allows the material to bounce 20% higher).

Footnotes

  1. Go with the flow - Peter Hollamby, 2005
  2. MIT Website on Silly Putty
  3. “Forty Years of Firsts: The Recollections of a Dow Corning Pioneer," by Dr. Earl L. Warrick, McGraw-Hill Publishing Company, New York, 1990, pp. 27-28.

See also

External links

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