Silly Putty facts for kids
Silly Putty is a famous stretchy toy made from silicone polymers. It has bizarre and fascinating physical properties that make it act like both a solid and a liquid. You can bounce it like a rubber ball, stretch it like chewing gum, or snap it in half with a quick pull. If you leave it alone on a table, it slowly melts into a flat puddle over time.
Scientists classify Silly Putty as a viscoelastic substance and a non-Newtonian fluid. This means its thickness and behavior change depending on how much force you apply. The material was originally created by accident during World War II while chemists were trying to invent a replacement for natural rubber.
Today, the name Silly Putty is a registered trademark owned by Crayola LLC. Millions of plastic eggs containing this unique substance have been sold all over the world. It remains one of the most popular and scientifically intriguing novelty toys in history.
Contents
Discovering the Science and Chemistry Behind Silly Putty
Silly Putty is not just an ordinary toy. It serves as an exciting chemistry lesson in a small plastic egg. Its unique behavior comes from synthetic chemistry and molecular physics.
What Are Polymers and Silicone Molecules?
To understand how Silly Putty works, it helps to look closely at polymers. A polymer is a large chain of repeating smaller molecules called monomers. Think of a polymer like a long string of beads.
Most traditional plastics and natural rubbers are made from long chains of carbon atoms. Silly Putty is different because its main backbone is made of silicone. Silicone chains consist of alternating atoms of silicon and oxygen.
The primary chemical ingredient in Silly Putty is polydimethylsiloxane (often abbreviated as PDMS). These long silicone chains can slide past one another smoothly. To turn this liquid silicone oil into putty, chemists cross-link the chains using boric acid. Cross-linking creates flexible chemical bridges between the long polymer strands. These bridges act like tiny molecular springs that hold the chains together without making them rigid.
The Exact Recipe and Chemical Composition
The classic coral-pink Silly Putty uses a precise mixture of ingredients:
- 65% dimethylsiloxane (silicone polymers joined by boric acid)
- 17% silica (powdered quartz crystals that add strength)
- 9% Thixatrol ST (a modified vegetable oil derived from castor oil)
- 4% polydimethylsiloxane (free silicone oil that adds softness)
- 1% decamethyl cyclopentasiloxane (a smooth silicone fluid)
- 1% glycerine (a humectant that keeps it moist)
- 1% titanium dioxide (a bright mineral pigment)
These ingredients are carefully heated and blended to form the squishy dough we know today.
How Does a Non-Newtonian Fluid Work?
Sir Isaac Newton described standard liquids, such as water and cooking oil, as having a constant viscosity (thickness). Water flows at the same rate whether you stir it gently or splash it wildly.
Silly Putty is a non-Newtonian fluid because its viscosity changes based on applied force or stress. Specifically, it is a dilatant or shear-thickening material.
- Slow force: When you pull Silly Putty gently, the cross-linked polymer bonds have time to unlock and slide. The putty stretches into thin ribbons or flows downward like thick molasses.
- Fast force: When you hit the putty with a hammer or throw it against the floor, the polymer bonds lock up instantly. The molecules do not have time to rearrange, causing the material to behave like an elastic solid and bounce or shatter.
This combination of fluid flow and elastic rebound is known in physics as viscoelasticity.
Strange Physical Properties and Fun Experiments
Silly Putty exhibits many curious physical behaviors that make it fun for experiments at home or in the science lab.
Bouncing, Stretching, and Snapping
If you roll Silly Putty into a tight sphere and drop it, it can bounce up to 80% higher than a standard rubber ball. The temporary molecular bonds absorb kinetic energy and spring back rapidly.
However, if you grab the putty with two hands and yank it apart suddenly, it breaks cleanly with a sharp snap. You can even see flat edges along the break line before the molecules slowly relax again.
Lifting and Transferring Newspaper Prints
For decades, kids used Silly Putty to copy comic strips from the Sunday paper. When pressed firmly onto a newspaper page, the putty lifted the ink. Kids could then stretch the putty to distort the faces of cartoon characters.
This trick worked because old printing presses used petroleum-based inks. The silicone in the putty naturally dissolved and lifted these mineral oils. Modern newspapers often use soy-based inks, which bond more tightly to paper fibers and do not transfer as easily.
Temperature Effects on Putty Viscosity
Temperature dramatically affects how the polymer chains move inside Silly Putty:
- Warm water: Submerging the putty in warm water adds thermal energy, making the polymer chains slide much faster. The putty becomes very soft and melts rapidly into a puddle.
- Freezing temperatures: Chilling Silly Putty in a freezer slows down the molecular movement. The cold putty becomes brittle like glass and can shatter if struck firmly with a mallet.
Cleaning Up Stuck Putty
Because Silly Putty flows over time, it can seep deep into carpet fibers or fabric if left on furniture. Regular soap and water often fail to remove it because the silicone repels water.
Rubbing alcohol or alcohol-based hand sanitizers dissolve the cross-linked bonds quickly. Once the alcohol breaks down the silicone structure, the putty can be blotted away with a clean towel.
The Accidental History and Origin of Silly Putty
Like many great inventions in science, Silly Putty was created by accident during a wartime crisis.
The World War II Rubber Crisis
During World War II, military forces needed enormous amounts of natural rubber for vehicle tires, aircraft components, rafts, and waterproof boots. In the 1940s, access to rubber plantations in Southeast Asia became restricted due to the global conflict.
The United States government asked industrial chemists to invent a synthetic rubber substitute using abundant raw materials. Laboratories across the country began experimenting with various chemical mixtures.
The Inventors: James Wright and Earl Warrick
Credit for creating the original bouncing silicone putty is shared by multiple scientists who conducted independent research during the 1940s.
In 1943, James Wright, a Scottish-born chemical engineer working for General Electric in Connecticut, mixed silicone oil with boric acid. The reaction produced a sticky, bouncy compound with remarkable elasticity.
Around the same time, Dr. Earl Warrick and Rob Roy McGregor at Dow Corning also developed a similar bouncing silicone material.
Both teams discovered that while the new compound was non-toxic, mold-resistant, and bouncy, it lacked the tensile strength needed to make heavy-duty truck tires or military gas masks. As a result, the government set the sticky compound aside.
Peter Hodgson Turns a Flop Into a Worldwide Sensation
In 1949, a toy store owner named Ruth Fallgatter discovered the strange bouncing material and featured it in her catalog. She worked with an advertising copywriter named Peter Hodgson to market it.
When Fallgatter decided to move on to other products, Hodgson realized the compound had huge commercial potential. In 1950, he borrowed $147 to buy a bulk batch of the silicone putty. He divided it into small portions weighing 1 oz (28 g), placed them inside colorful plastic egg shells, and named the product Silly Putty.
The toy became an overnight sensation after a writer for The New Yorker magazine praised the odd substance. Hodgson received orders for over 250,000 eggs in just three days.
Silly Putty Timeline
- 1943: Chemists invent bouncing silicone putty while searching for synthetic rubber.
- 1949: Ruth Fallgatter lists bouncing putty in a novelty catalog.
- 1950: Peter Hodgson packages the substance into plastic eggs and coins the name Silly Putty.
- 1957: Silly Putty airs its first television commercial during the Howdy Doody Show.
- 1968: Astronauts on the Apollo 8 mission carry Silly Putty into orbit around the Moon.
- 1977: Binney & Smith (the makers of Crayola) purchases the Silly Putty brand.
- 2001: Silly Putty is inducted into the prestigious National Toy Hall of Fame.
Modern Varieties and High-Tech Innovations
Over the decades, Silly Putty has evolved with exciting new colors, formulas, and scientific uses.
Glow-in-the-Dark and Color-Changing Putties
Today, Crayola and other toy manufacturers produce putties with special additives:
- Glow-in-the-Dark: Contains phosphorous compounds that absorb light energy and glow in the dark for hours.
- Metallic and Glitter: Infused with tiny reflective flakes for a shimmering finish.
- Thermochromic: Uses heat-sensitive pigments that change color when warmed by human hands.
Magnetic and Conductive Putties
Specialty manufacturers blend iron micro-particles into silicone putty to create magnetic putty. When placed near a strong neodymium magnet, the putty slowly reaches out, engulfs the magnet, and pulls it inside.
Scientists have also created conductive putties by adding microscopic carbon particles or graphene. These putties can conduct low-voltage electrical currents and change their electrical resistance when stretched.
Practical and Scientific Applications
Silly Putty is far more than a fun toy. Its unique physical properties make it valuable across many industries:
- Hand Therapy and Rehabilitation: Occupational therapists use therapeutic putty of varying densities to help patients strengthen fingers and hands after surgery or injury.
- Space Exploration: During the Apollo 8 spaceflight, American astronauts used the adhesive putty to keep tools and notebooks from floating around in zero gravity.
- Telescope Mirror Polishing: Astronomers at the Steward Observatory have used custom putty backings to hold and polish large telescope mirrors without creating uneven pressure.
- Advanced Nanotechnology Sensors: Physicists at Trinity College Dublin mixed graphene into Silly Putty to create ultra-sensitive pressure sensors capable of measuring the impact of tiny spider footsteps.
- Hobby Crafting and Cleaning: Model makers use putty to mask sections of scale models before airbrushing paint, while mechanics use it to pick up lint, dust, and metal shavings from tight crevices.
See Also
In Spanish: Silly Putty para niños
- Blu Tack
- Flubber (material)
- Non-Newtonian fluid
- Polymer chemistry
- Slime (toy)
