How to Make Blacklight Ink

Writing secret messages with invisible ink is easy to do if you have a black light to decode the message. Many household substances like detergent and petroleum jelly contain phosphors, which are able to absorb invisible radiation and convert it into visible light that your eyes can detect. In this case, the phosphors absorb ultraviolet radiation from the black light and give off visible light, creating a glow-in-the-dark effect.

Difficulty: Easy

Instructions

Things You'll Need:

• Petroleum jelly or liquid detergent
• Black light
• Paper
• Small paint brush

1. Dip your paint brush into the petroleum jelly or liquid detergent and write a message on the paper. You can also just use your finger if you don't mind being a little messy.

2. Turn off the lights and close the shades if there is a lot of light outside your window.

3. Turn on the black light and shine it on the paper to reveal the secret message.