Secret Message – FriXion Pen

Make a message appear or vanish using a special heat and friction activated ink.

Give someone special a note that requires heat to decode the message.  You won’t believe what the ink in this pen will do. Your message can appear or vanish on command… and most people don’t even know that the ink works this way.

SICK Science® is a registered trademark of Steve Spangler, Inc. All Rights Reserved.

Experiment Materials

  • Friction pen (like Pilot's friXion pens)
  • Regular ink pen
  • Lighter
  • Paper

Experiment Videos

Experiment

1

Using the regular ink pen, write the message that you want your recipient to read on the paper.

2

Now, cover the secret message up with the friction pen. Turn the letters into shapes or designs, scribble all over the words, or anything else that makes your secret message unreadable.

3

When your secret message is ready, there are a number of different methods you can use to heat the paper in order to reveal the message:

  • Using a lighter is the quickest and easiest way, but always have an adult present when you use a lighter.
  • You can hold the message over the top of a toaster.
  • You can use a pencil eraser. Just erase over the entire message.

4

Stick your secret message paper in the freezer.  Once the local temperature on the ink drops below 14°F, the ink will once again turn black.  Reappearing art!

How Does It Work

The friction pen uses ink that is sensitive to heat. At temperatures that range between 15°F and 140°F, the ink will appear black when writing on paper. But when local temperature exceeds 140°F, like when held near a heat source or when friction is concentrated on a certain spot, the ink becomes clear.

This specially formulated ink is called thermochromic ink and can actually be formulated into different colors and to change color at different temperatures. Believe it or not, this probably isn’t the first time you’ve seen or used thermochromic ink. This special ink has been used in mood rings and heat sensitive labels.