How to Make a Folding Egg
An extension of the classic Rubber Egg experiment.
The Folding Egg activity is actually an extension of the classic Rubber Egg experiment with a really fun twist. Just imagine the look on your friends' faces when you show them an egg and then proceed to fold it in half several times until it forms a small white ball! Wait... it gets better. Just bounce the "folded egg" between your hands and the egg reappears!
- Raw egg
- Pin or a thumb tack
- Long needle or plastic coffee stirrer
- Tall glass
Warning: Always wash your hands well with soap and water after handling raw eggs. Some raw eggs contain salmonella bacteria that can make you really sick!
- The first step is the trickiest and requires a little practice. You'll need to blow out the inside of the egg without damaging the egg (too much!). Use a sharp pin, a thumb tack or the tip of a sharp knife (yes, with the help of an adult) to poke a small hole in both ends of the egg. The hole should be about an 1/8 of an inch in diameter. Don't be frustrated if you crack a few eggs before you get the hang of it.
- The next step is to scramble the inside of the egg to break the yellow yolk and to blow the liquid out through one of the holes. The best way to break the yolk is to poke a long needle or something similar (like a plastic coffee stirrer) through the hole and to carefully poke around inside the egg.
- Once the yolk is broken and the egg is "scrambled," it's time to blow all of the liquid out of the egg. One method is to clean off one end of the egg, cover the hole with your mouth, and blow the egg liquid out the other hole. Of course, it's best to hold the egg over the sink as you're doing this. People who are concerned about using their mouth may experiment with other methods or may elect not to try the activity.
- Place the hollow egg in a tall glass or jar and cover the egg with vinegar. You want the egg to be completely submerged in the vinegar, which means that you may need to place something on top of the egg to push it down or to try to fill the inside of the egg with vinegar to weigh it down.
- Leave the egg in the vinegar for up to 10 days or until all of the shell has dissolved. Some eggshells will take longer to dissolve than others because every egg is unique. For the first few days, bubbles of carbon dioxide gas will form on the shell. The vinegar is dissolving the calcium carbonate in the shell and producing bubbles of carbon dioxide at the same time. When the bubbles stop forming, it's a good indication that the eggshell is completely dissolved. (In the video Steve uses 3 M HCl to speed up the process.)
- Once the bubbles have stopped forming (again, this could be up to 10 days so be patient!) pour off the vinegar and carefully rinse the egg with water. The egg looks translucent because the outside shell is gone! The only thing that remains is the delicate membrane of the egg. You've successfully made an egg without a shell. Okay, you didn't really make the egg. The chicken made the egg. You just stripped away the chemical that gives the egg its strength.
- Carefully squeeze out all of the water from the egg membrane. Gently blow a little air into one end of the egg and the egg will puff up. Hey, it looks like a real egg! Slowly squeeze the egg in your hand and it will look like you crushed the egg. Just carefully toss and bounce the "folded egg" in your hand to allow the air to slowly work its way back into the egg. The egg magically restores its shape.
- Dust the egg membrane with some baby powder (sometimes called Talcum powder). Try to get some of the powder inside the egg as well. The powder will help keep the egg membrane from drying out and cracking - and it makes the egg look even more real.
How does it work?
The acetic acid in the vinegar breaks down the calcium carbonate in the eggshell, and the bubbles that form on the surface of the egg are carbon dioxide gas. Eventually the hard shell of the egg disappears entirely and all that remains is the egg membrane. Because you have already blown out the contents of the egg, the membrane is just full of air. You can fold it up and the air will sneak out the tiny hole in the membrane you used to blow out the egg. The membrane will compress down into practically nothing. As you gently shake the "folded egg," the air will re-enter the membrane, expanding back into its original shape and volume.
A Little Magician's Secret - The Folding Egg is a classic science magic trick dating back to the early 1900's. To perform the illusion, the magician would place the inflated egg in an egg carton along with several real eggs. He carefully removed the "special" egg and proceeded to squeeze the egg in his hand. With a little slight of hand, the egg magically seemed to vanish. The magician then showed his audience a clear, empty glass. While showing the glass, he secretly dropped the crumpled up egg membrane into the glass being careful to cover the bottom of the glass with his other hand. "I'll make the egg magically appear by simply shaking the glass." With a little shaking and lots of showmanship, the audience watched as the egg magically reappeared in the glass. Ta da!
How to Make a Folding Egg
January 1st, 2013
Click the thumbnail below to see the video.
THIS IS SO FUN
Jackie R. - January 5, 2013
I tried this at home and it was so fun. My patents freaked out and so did the rest of my family. I can't wait to this years science fair, i'm going freak my teacher out!!!
Don't put the egg yolk down the sink!
Sharon Smith - January 2, 2013
This experiment is cool and lots of fun for kids. Just don't blow the egg into the sink. Fats from the egg yolk contributes to grease clogs in sewer lines, leading to sewer spills and unhealthy conditions in the environment and your community. Put all fats, oils, and grease in the trash!
Shareeni - October 26, 2012
This experiment was pretty cool and it definitely awes your friends. I did this experiment with a brown egg and I soaked it in the vinegar for about 10 hours and the eggshell completely dissolved in the morning. Is that supposed to happen?
Really, really cool!
Mimi - April 25, 2011
I enjoyed doing this experiment very much! It was so cool and exciting. I loved it so much, I chose to do it for my science fair project. Every thing worked out fine; the egg came out perfectly like it was supposed to. This a great project to do!
Awsome with a side effect
Doug - April 25, 2011
I trid this experiment and love it. all my teachers loved it. The only thing that went wrong was I made a second egg and let it sit too long in vinigar and it got moldy. Also the egg never loses all the calcium carbonate in the vinigar so I got it off when I first played with it. I also recoment rinsing it aftr it comes out of the vinigar