Invisible Ink from the Kitchen Shelf

In the last blog post we saw how we could use lemon juice to write a note in invisible ink. This beats buying commercial invisible ink as you can get lemon juice from the kitchen any time you like and at a much more reasonable rate. Is lemon juice the only kitchen ingredient that can be used to make invisible ink? No, there are a few more. Consider this a science project to identify other sources of invisible ink in the kitchen.

Equal parts of baking soda and water make a fairly good invisible ink. Once you make the solution use a simple ear bud made of cotton to dip and write your secret message. Wait for the paper to dry. To read the message take some grape fruit concentrate and dip a paint brush in it. Paint the paper with the grape fruit concentrate to make the message appear.

Another good invisible ink that you can find easily in the kitchen is milk. Take some in a bowl and use with a cotton ear bud to print out your note on paper. Once the paper has dried and you want to make the message visible hold it against the light bulb of your table lamp. As the paper heats up your message will appear clearly. Can you find out more things to use as invisible in in this science project?