Science Box - Spy Girl Writing

Sorry, but I can't find where I got this one from originally.  Also please forgive the annoying purple mark that has made its way into all my pics!

What you need:

A lemon
An earbud
Iodine
Spray bottle
Paper

I bought 'iodine tincture' from a high street chemist.  A word of warning, this iodine stained my hands so be careful not to stain anything with it.

Step 1

Cut the end of the earbud to make a writing nib.

Step 2

Dip the nib into the lemon and writing a message on the paper.  You will be able to see what you have written but once it has dried it will be hard to read, although not completely invisible.

Step 3

Add a couple of drops of iodine into some water.  Be careful not to stain anything with the iodine.  I made mine up into a little spray bottle.  You could 'paint' the solution but you risk drenching the paper.

Step 4

Lightly spray the paper with the solution.  Hey presto!  The secret message is now revealed.

I am sure my daughter will love this and will be able to send secret messages time and again.  It is simple but fun.