Once the soap molecules are introduced to the bowl, the surface tension will not come back. If you want to repeat this science trick, you will have to rinse the bowl out and use new toothpicks.

Project #4: Invisible Inks

Items Needed for Ink 1:

  • Paper
  • Lemon juice
  • Cotton swab or small paintbrush
  • Warm lightbulb, warm oven, or other heat source

To create Ink 1, write a message onto the paper with lemon juice. Allow the juice to dry completely. With your parents' consent, hold the paper close to (but not touching) a warm lightbulb to make the message visible.

Why Does This Happen? 

Lemon juice is acidic. When the acid is heated up, it darkens more quickly than the paper.

Items Needed for Ink 2:

  • Paper
  • Baking Soda
  • Water
  • Purple grape juice concentrate
  • Cotton swab or small paintbrush

To create Ink 2, mix equal parts baking soda and water. Using this mixture, write a message onto the paper. Allow the paper to dry completely. Next, paint the paper with grape juice. Your message should not be invisible any longer.

Why Does This Happen? 

Baking soda and grape juice produce a chemical reaction, causing the message to have a different color than the rest of the paper.

Now that you know some science tricks of your own, remember there are scientific principles that allow illusions to work!  


Melissa Pinkley enjoys life with her husband, Wes. They learn a lot from their four children: Ben, Micah, Levi and Abigail. Homeschooling goes on 24/7 for the whole Pinkley family. They have been homeschooling for 10+ years.  The Lord is gracious and continues to help them follow Him. 

This article was originally published in the Jan/Feb '10 issue of Home School Enrichment Magazine. Now, get a FREE subscription to the HSE Digital Edition! Visit www.HSEmagazine.com/digital today to get immediate access to the latest edition!