Hooked on Science: Teflon tape secret message

Materials:

• Teflon tape
• Pen
• Ruler

Instructions:

STEP 1: Cut 4 inches of Teflon tape. Attempt to stretch the tape lengthwise without breaking the tape. Using the ruler, measure the length of the tape. Did the length change?

STEP 2: Cut 4 inches of Teflon tape. Using the ruler, measure the width of the tape. Attempt to stretch the tape widthwise without breaking the tape. Using the ruler, measure the width of the tape. Did the width change?

STEP 3: Cut 4 inches of Teflon tape. Using the pen, write a secret message on the tape. Stretch the tape widthwise without breaking the tape. What happened to the message? Give the tape to a friend and have them stretch the tape lengthwise without breaking the tape. What happened?

Explanation:

The Teflon tape is made of a polymer, which is a bunch of molecules linked together to form long chains. The Teflon tape polymer chains are aligned side-by-side and parallel to each other in a lengthwise direction. This makes it difficult to stretch the Teflon tape lengthwise without breaking the tape. Widthwise, however, the tape stretches easily. Because of this, when a message is written on the tape, then stretched widthwise, the message becomes unreadable. When the tape is stretched lengthwise, the message becomes readable.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website hookedonscience.org for webcasts and experiments.