Invisible Ink Pen Pals Soda

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This DIY is a great way for your kids to mail secret messages to friends they haven't seen in a while. From ARM & HAMMER™ Summer Camp Counselor Amber Kemp-Gerstel

Ingredients & Supplies

Craft Time: 5 minutes
Yields: secret messages

  • ½ cup ARM & HAMMER™ Baking Soda
  • ½ cup water
  • White printer paper
  • A safe heat source, like a light bulb (optional)
  • 8 ounces purple grape juice
  • Paintbrush
  • Measuring cups


  1. Mix equal parts water and ARM & HAMMER™ Baking Soda.
  2. Dip a paintbrush in the solution and use to write a message on your white printer paper. For example, “Let’s order pizza tonight.”
  3. Allow the ink to dry.
  4. To reveal your secret message, you have two options: You can gently paint over the message with purple grape juice, or you can hold the paper up towards a light bulb or other heat source.


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