G1 has been asking for “invisible ink” ever since he read about using lemon juice to write hidden messages from one of Enid Blyton’s adventure books so when I stumbled on a Secret Spy Kit, I decided to get it for some secret message fun at home…
What’s in the Kit?
- Code Book – that teaches kids various secret code methods, like the “Pig Pen” and “Morse Code”
- Decoder Card – to reveal hidden messages
- Code Torch – for sending morse code
- Secret Marker Pens – invisible ink and revealer
The activities are pretty straight forward and easy to DIY if you have the time and patience for it.
There are two pens:
- secret marker – for writing hidden messages
- developer marker – for revealing the hidden message
You can also make your own “invisible ink” with lemon juice. To reveal the messages, warm the paper with a hairdryer, a candle, a desk lamp, or leave it under the sun for a while.
Reveal hidden messages with a decoder card.
You can also make your own decoder card using red cellophane paper:
More about them here: Designing for Decoder Glasses, Print and Web.