Tinker: Rubber Egg Experiment

by STEM Scouts


You might not even recognize that this is a chicken’s egg after you’re done with this experiment. It could even pass for an “alien egg.” This easy bit of science is simple to do. It requires some patience and planning, but the payoff is worth it. Here’s how to make an egg squishable, bounceable and glow in the dark.


  • Distilled White Vinegar
  • Water
  • Egg
  • Yellow Highlighter
  • Black Light
  • Jar
  • Safety Gloves (Optional)


  1. Place your egg in the jar and fill the jar enough to cover the egg with vinegar. You should notice bubbles forming on your egg shortly after placing it in the vinegar. Let the egg sit in the vinegar for 24 hours.
  2. After 24 hours, remove and replace the vinegar with new vinegar.
  3. Put on your safety gloves. These are not imperative, but recommended as the next step can be messy!
  4. Remove the plastic cap from the end of the highlighter and slide the ink cartridge out. Using your fingers, squeeze the ink into the jar.
  5. Lightly stir the liquid in the jar to mix the ink and vinegar together, then close the jar.
  6. Let the egg sit anywhere from 2-7 days.
  7. Next, remove the egg from the vinegar by pouring it into your hand, then rinse it with water.
  8. Stick it under a blacklight to watch it glow. Feel free to gently bounce, roll and squeeze your “naked” egg. But be careful, it can still break open!
  • Don’t even think about eating this egg. After all, it’s still raw and has been soaking in vinegar unrefrigerated for almost a week.
  • Try conducting this experiment with a few eggs at a time and remove them from the vinegar at different times, letting one egg sit for two days, another for three, a third for four, and so on. How is each of the eggs different when they spend more or less time in vinegar?
  • Do you notice a difference with or without the highlighter ink? How do you think the ink gets into the yolk of the egg?
  • How does the vinegar soak affect the weight of each of the eggs?

How Does It Work?

The answer is chemistry! Vinegar is an acid and the egg’s shell is made largely of calcium carbonate. Exposing the shell to vinegar causes a chemical reaction that dissolves it and releases carbon dioxide, which gives us our bubbles, in the process.

Now, you might ask, “If the shell is gone then how does the egg remain intact?” For that, we have to look at the anatomy of an egg. An egg has a number of membranes, two of which are just on the inside of the shell. They are called, simply enough, the outer and inner membranes. There’s a third membrane that surrounds the yolk called the vitelline membrane. Luckily, vinegar only dissolves the shell and exposes these soft membranes, but since they aren’t very strong, the egg can still break easily.

How did the highlighter ink get inside the egg? Well, those membranes are semipermeable, meaning water and other substances (vinegar and ink here) can easily pass through. This process is called osmosis. If you didn’t want to use highlighter ink, you could use food coloring for a similar effect.



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