INVISIBLE INK PRINTER
TAKE A NEW TWIST ON LEMON JUICE.
JUICY SECRETS: Make your top-secret messages a mystery.
Photograph by Garry McLeod
Lemon juice has been used as invisible ink for centuries. Messages written in lemon juice are invisible to the naked eye. However, when brushed with a mix of iodine and water, they become quite visible.
You can use an updated version of this technique by modifying an HP ink cartridge so that it prints in lemon juice instead of ink. Here’s how to do it.
TOOLS & MATERIALS
HP inkjet printer ...
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