Extreme Science: Penny Shine

Join us every Saturday morning for Extreme Science with Radical Rick. This week Rick shows us how to 'shine a penny' with science!

Here's what you need for this experiment:

  1. Several tarnished (dark) pennies
  2. Small plate
  3. Hot sauce or taco sauce
  4. Sink (to rinse pennies)
  5. Electrical tape (optional)
  6. Adult supervision


  1. Place your pennies on your plate.
  2. Pour some taco sauce over your pennies.
  3. Using your finger, gently rub the taco sauce into the penny. Do not lick your hands afterwards as the pennies are filthy and disgusting! Also, be careful if you have any small cuts in your fingers as the taco sauce may irritate it.
  4. Let the pennies sit for 2 – 3 minutes while you wash your hands.
  5. Rinse the pennies off and check out the difference!

What is going on?

There are actually several things that you can use to clean pennies such as lemon juice and salt, vinegar and salt or, your favorite taco sauce! If you took the ingredients of the taco sauce such as tomato paste, vinegar or salt and tried to clean the pennies separately, you wouldn't get them very clean. When salt is dissolved in the vinegar as it is in the taco sauce, the salt breaks down into sodium and chloride ions. The chloride ions will combine with the copper in the penny to remove the tarnish form its surface.

Try this:

  • Try covering half of a penny with some electrical tape prior to cleaning it with the taco sauce. Afterwards, when you remove the tape you can see how much tarnish was actually removed.
  • Try a mixture of vinegar and salt to clean some more pennies. Does this solution work any better than the taco sauce?
  • Try mixing a solution of lemon juice and salt to clean some pennies. How does this solution compare to your previous attempts?
  • Try using different brands of taco sauce. Is there any difference in how well each brand cleans the pennies?