Science Experiments

Secret messages - what makes an Invisible Ink?

Sun, 15th Feb 2009

Listen Now    Download as mp3 Part 1,2 from the show The Science of Love

What you Need


Some paper


A toaster

Cotton Buds

Cotton buds or a paint brush

Variety of inks

Various kitchen materials such as fruit juice, sugar, salt, bicarbonate of soda etc.

What to do

If any of your materials are not liquid, then try dissolve them in water.

Drying paperUsing a cotton bud write on your paper using each of your invisible inks.  If you're trying out lots of different inks, you may want to make a note in a normal visible ink which one is which, or you may loose the writing when the ink becomes invisible!

Allow the paper to dry out.

How invisible is your ink?

Now you should try developing the ink, to do this turn on your toaster, and hold the paper over the top until the paper starts to brown or you can read your message.

Which of your inks work?

Be careful, a toaster is hot, so don't touch the toaster or the paper while it's over it.  Also don't put the paper inside the toaster as it is possible it may catch fire.

What may happen

You should find that many of the inks will develop as you heat them up, and your message should become visible.  Some chemicals will make better inks than others,and may develop at different rates.

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