Vanishing Styrofoam Cups | Science Experiment

Vanishing Styrofoam Cups - In our Vanishing Styrofoam Cup experiment, pieces of Styrofoam will vanish. Is it magic? Or is it science? Read on to find out!  

Styrofoam (polystyrene) is one of the most complex and difficult materials on earth when it comes to decomposition. Styrofoam is actually a type of plastic. It is made of up atoms that are bonded to each other strongly and can take anywhere between 500 to 1 million years to decompose. Believe it or not, there is a way to make an entire cup of Styrofoam vanish in a matter of seconds. How can this be possible? It doesn’t involve fire, so there’s no acrid smoke released (polystyrene produces harmful fumes when it is burned). Although it seems like magic, it is just some really cool science. Knowing the science behind what takes place in our melting Styrofoam experiment is pretty darn awesome!

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Experiment Materials

  • Acetone*
  • Styrofoam Cup
  • Pie Plate
  • Adult Supervision
  • *Use acetone in a well ventilated area or outdoors!

Experiment Videos



In a well-ventilated area, cover the bottom of a pie plate with a thin layer of acetone.

Disappearing Styrofoam Cup - Step 2


Carefully place the Styrofoam cup into the center of the pie plate.

Disappearing Styrofoam Cup - Cover Image


Stand back and observe. Watch in amazement as the cup disappears!

How Does It Work

Styrofoam is actually the common, registered trademark name for a material called “polystyrene.” Products manufactured with polystyrene began in the 1930s. In the 1960s, it was first used in coffee cups because its insulating properties. (This means it keeps your hot drinks hot by slowing heat transmission. It also keeps your cold drinks cold.)

Polystyrene is the long-chain molecule of the monomer (smaller molecule) styrene. Polystyrene is a polymer that is actually a type of plastic. The acetone is a solvent that easily breaks down the polystyrene, releasing the little air pockets trapped inside and leaving very little residue at the end. In other words, when you combine Styrofoam and acetone, the polystyrene will completely dissolve! 

As a science teacher, science enthusiast or an environmentalist, you are aware of the bad effects that Styrofoam has on our environment and the space that it takes up in landfills. So why not just use acetone to dissolve waste polystyrene? Problem solved, right? Not quite! Unfortunately, acetone presents its own environmental and energy consumption issues so melting Styrofoam in giant vats of acetone is not a good solution to the polystyrene abundance in landfills. 

Take It Further

Another spin on the Styrofoam and acetone melting effect is our Vanishing Peanuts experiment! 



If you had a blast with this melting Styrofoam experiment, there’s more fun science activities at Steve Spangler Science. Whether you’re looking for at-home science experiments or fun, memorable activities for a STEM club or science class, you’ll find great ideas here. Check out our online experiment library for dozens of science experiments that will blow your mind — and demonstrate the principles of chemistry, food science, physics and more! Sign up for our Steve Spangler Science Club, too, for monthly all-in-one kits!

Safety Information

WARNING: Please follow all of the manufacturer’s safety precautions listed on the container of acetone. Acetone solvent is very flammable. Keep away from all flames. 

Real-World Application

Currently about 200 million cubic feet per year of polystyrene “loose fill” (packaging material) is used in the United States; Styrofoam is estimated to fill up about 30% of landfills globally. Although some companies try and reuse the packing material, most of the polystyrene is disposed of in landfills all over the world. As students of science, we need to carefully examine such products and ask these questions: how is the material made and what happens to it after it is used? One of the properties of polystyrene loose fill is that it does not compress easily. While this is beneficial when trying to protect something from being crushed or broken, it poses a problem when trying to dispose of it in a landfill. As a result, environmentally conscious companies sought a solution to these problems. 

One such solution is called Eco-Foam loose fill. Eco-Foam provides both the ease of use and the cushioning of polystyrene, yet gives us many other re-use or disposal options for the future. It also readily decomposes in water and can be re-used for your own packages. It can also be disposed of by putting it into your compost pile, watering it into your lawn or washing it down the sink.

Eco-Foam is made almost entirely from an annually renewable resource: corn. The remaining ingredient is a water-soluble organic polymer called “polyvinyl alcohol.” This organic polymer is made from carbon, hydrogen and oxygen — you know, the building blocks of life. When polyvinyl alcohol is exposed to water, naturally occurring bacteria feed on this organic polymer. Under wet conditions, the bacteria will use the starch (which is also composed of carbon, hydrogen and oxygen) and polyvinyl alcohol as food to begin the cycle of life again.

Many people feel that the answer to our solid waste problem is recycling. While this method will go a long way to help our solid waste problems, it is not the whole solution. One good suggestion is to use as little of the material as possible. Secondly, it makes sense to use a natural product (instead of a synthetic product) that will break down when we are finished using it. We must remember how to reuse!

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