Today Jon, Ellie & I tested out three different invisible inks, using ingredients that most people probably already have at home! (Definitely scores high on the “simple activity” meter!!) This would be fun for all ages!
Here’s what you need to try this with your kiddos:
You’ll be using lemon juice, milk & onion juice for the three different inks in this project. We used juice freshly squeezed from a lemon, so I’m not sure whether the kind from the bottle works the same…but you can always give it a try!
For the onion juice, you’ll cut an onion in half and then use a grater over a bowl. As you grate the onion, the pieces and juice will fall into the bowl. You don’t need a ton, thankfully! (My eyes were watering by the time I finished grating, LOL!)
You will want separate bowls & paintbrushes for each of the invisible inks! Here are the steps we followed:
In testing the three inks, we felt that the onion juice dried the best (least noticeable on the white paper) and showed up GREAT after heating in the oven. However…it STINKS! Jon refused to paint with it at all (he’s very sensitive to smell).
Sooooo…even though it worked best out of the three, we concluded that if you were truly attempting to be secretive and keep others from noticing your hidden message – onion juice probably would not be the invisible ink you’d want to use. 😂
Want to know how this worked?

Let me know if you & your family try this out! I would love to know if you have a similar experience!
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