The result? A colorful miniaturized piece of artwork on a much thicker piece of plastic. You could easily create all sorts of mini-objects, from toys to zipper pulls to earrings.
Here’s a look back at the kind of fun people used to have with these shrink art toys, how they were invented, how they work — and how you can make them today.
Shrinky Dinks inventor speaks to local students (1987)
Excerpted from an article by Randy Rendfeld – Anderson Daily Bulletin (Anderson, Indiana) March 2, 1987
The inventor of the “Shrinky Dinks” told Edgewood Elementary students not to let their dreams shrink.
Betty Morris of Brookfield, Wisconsin, said 14 years ago she had an idea — to make artful objects from shrinkable plastic. Her company, K&B Innovations Inc., since has sold about 365 million worth of Shrinky Dinks products in 14 countries.
Morris said in the beginning, she made numerous calls trying to find a plastic that would shrink. Finally, she found it.
But there was a catch. She would have to buy a 1,000-pound roll of it. Instead, she sent for samples of the plastic.
The shrinkable art was an instant success with children she knew. So, Morris and a partner eventually bought 1,000 pounds and packaged it.
In those days before colored pencils could be used to decorate Shrinky Dinks, Morris said her product sold so quickly in Brookfield, Wisconsin, “Sears ran out of permanent-ink markers.”
Sales expanded to 26 stores, and in five months, more than 150,000 worth of shrinkable plastic had been sold. Morris said she had to “work around the clock” to keep up with demands.
“Some people have said kids don’t have a thing left to invent,” Morris said. “That’s not true.”
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Writing something on paper is the mechanical part of creative thinking, but “it has to start here,” Morris said, pointing to her head. “This is where creative thinking happens.”
Mayor Thomas McMahan and Dr Thomas Neat, Anderson Community Schools superintendent, took part in a brief Shrinky Dinks baking session in the gym.
McMahan told students, “When I was your age, I used to hear, ‘There’s nothing new under the sun…’ But you wouldn’t recognize our world from 40 or 50 years ago.” He referred to recent inventions such as the microwave oven.
Morris unveiled a cast of “dinky” cartoon characters, showing pictures of them.
Within two weeks, Morris said she hopes to have a decision from ABC-TV concerning the fate of the cartoon “dinks” who can fly and shrink by using “shrinky dust.”
Vintage Muppets ShrinkyDinks Playset
Produced by the Colorforms company
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How do Shrinky-Dinks work? We took a look
You might have played with these as a kid, and wondered how Shrinky-Dinks worked. Why doesn’t the plastic just melt, and how does it shrink so evenly?
Plastic magically goes mini
If you grew up in the 1970s or 1980s, chances are you remember having fun with these magical little bits of plastic.
You colored them in carefully, had mom fire up the oven and stick them in, and in a few minutes, you had colorful miniaturized plastic shapes you could use for zipper pulls, ornaments, keychains, or just for playing around.
One of the best things about these is that you don’t even have to buy the materials — you can simply recycle certain types of plastic you already have at home.
Better living through chemistry
Despite how awesome they look when they curl and shrink in the oven, there’s no magic involved. Shrinky Dinks are actually nothing more than sheets of polystyrene, a common type of plastic or polymer.
The polystyrene sheets are created through a process called extrusion — the material is heated to the melting point, then forced through a die to give it its shape.
As the material is forced through the die and then cooled on rollers, the molecule chains that make up the plastic are stretched out and lined up as well — biaxially-oriented, if you want the technical term.
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When you stick polystyrene in the oven, the heat causes the polymer chains to return to their most stable, random configuration — shrinking back down into a smaller but thicker piece of plastic.
While many other plastic objects simply get soft or melt entirely when heat is applied, biaxially-oriented polystyrene maintains its original mass — it just ends up thicker while taking up a smaller linear area.
Things to keep in mind
As we mentioned, not all plastics behave like this, so don’t go putting every piece of flat plastic you find in the oven. However, any clear plastic container that is marked with the “recycled plastic #6” marking is, in fact, polystyrene (styrofoam) and can be used like a Shrinky Dink (“shrink art”), provided you have appropriate ventilation.
Clamshell salad containers, meat trays, and even those clear lids from McDonald’s pancake containers are just two examples of this material found in common places.
So buy a kit if you want, or dig through the trash and make your own brand of art!
MORE: Colorforms, the vintage vinyl stick-on playsets that let kids stage scenes, create comics & dress dolls