SPY TECH
INVISIBLE INK PRINTER
TAKE A NEW TWIST
ON LEMON JUICE.
M016
BY MIKE GOLEMBEWSKI
JUICY SECRETS: Make your top-secret
messages a mystery.
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
Color ink cartridge
C-clamp
Hacksaw
Chisel
Latex gloves
X-Acto knife
Paper towels
True Lemon crystallized lemon juice ( 15 packets)
Small mixing cups ( 2)
Wide electrical tape
Zip-lock bag
2% iodine tincture
Photograph by Garry McLeod
92 Make: Volume 16
