Silly Putty

Silly Putty is a silicone plastic "clay", marketed as a toy for children by Binney & Smith Inc. It is another one of those scientific accidents on the way to solving another problem: finding a rubber substitute for the United States during World War II.

Silly Putty is a 0.47-ounce (13 gram) glob of plastic clay with unusual characteristics. It is packaged inside of an egg-shaped plastic container. When pressed on comics pages or other newspaper media, the loose ink transfers to the Silly Putty, which is then able to be stretched out, a source of amusement for many children. It bounces, revealing its rubber roots, it breaks when given a sharp blow, it can flow like a liquid when it is slowly stretched, and will melt into a puddle over a long enough period of time.

These unusual flow characteristics occur because Silly Putty is a viscoelastic liquid. Viscoelasticity is a type of non-newtonian flow, and indicates that the material will act as a viscous liquid over a long time period, but will act 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; it is more accurate to characterize it as a viscoelastic liquid. Silly Putty is primarily composed of the polymer known as polydimethylsiloxane, which is known for its dramatic viscoelastic character.

Since the 1980s, Silly Putty has been available in various colors, including glow-in-the-dark and metallic, and colors can be easily combined to make new color shades.

The origins of Silly Putty are controversial, as is typical of many inventions. Two researchers, working independently during the same time period, both came upon the product separately. The world may never know who was actually first.

Silly Putty was accidentally invented by James Wright of General Electric when he dropped boric acid into silicone oil. He was looking for a substitute for artificial 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. Earl Warrick 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 Peter Hodgson in 1949 after the marketing expert attended an informal "nutty putty" party. Renamed "Silly Putty" because of its main ingredient, Silicone, the product was a smash hit.

Raw Silly Putty polymer is available as Dow Corning (http://www.dowcorning.com/) 3179 Dilatant Compound. There are recipes for homemade silly putty using glue and boric acid. These produce a compound which is similar in chemical structure but is different in the elements which form that structure.

According to an MIT web page on inventions:

"Ironically, it was only after its success as a toy that practical uses were found for Silly Putty. It picks up dirt, lint and pet hair, and can stabilize wobbly furniture; but it has also been used in stress-reduction and physical therapy, and in medical and scientific simulations. The crew of Apollo 8 even used it to secure tools in zero-gravity."

A similar substance called Thinking Putty is available from many sites on the internet. Composed mainly of PDMS and Boric Acid and again available in a variety of colours, Thinking Putty bears large similarities to Silly Putty (minus the fact that it is shipped in 90g tins).

External links

• Template:US patent -- Treating dimethyl silicon polymer with boric acid
• Template:US patent -- Process for making puttylike elastic plastic, siloxane derivative composition containing zinc hydroxide
• Official Website of Silly Putty (http://www.sillyputty.com)
• Full story at MIT's Invention Dimension: Silly Putty page (http://web.mit.edu/invent/iow/sillyputty.html)
• Various Scientific Experiments done with Silicone Putty (http://www.puttyworld.com/thingstodo.html)
• American Chemical Society "What's that stuff?" page about Silly Putty (http://pubs.acs.org/cen/whatstuff/stuff/7848scit3.html)
• Firebox Thinking Putty (http://www.firebox.com/index.html?dir=firebox&action=product&pid=439)
• Crazy Aaron's Puttyworld (http://www.puttyworld.com) (Thinking Putty)
• ThinkGeek Smart Mass Thinking Putty (http://www.thinkgeek.com/cubegoodies/toys/5ac8)