Invisible Ink Treasure Map

Invisible Ink

Ahoy! Welcome to pirate month you landlubbers! We will soon make pirate me hearties out of the lot of yer! Pirates aren’t so bad laddies. Why I bet you’d love what we love to do. Any guesses? Ai! When we’re not looting other ships we be treasure hunting! But to get on our way we will be needing a real live, genuine treasure map. Between you and me us pirates have our sneaky ways of hiding treasure and making sure no else be finding them.

How? I hear you ask?

Oh come now. I couldn’t be telling you that could I?

That is… unless you become a jolly roger sailing pirate like me! Savvy?!

Yes?! Well shiver me timbers! Good, good!

Yo ho ho, well then! Lean in and listen closely…

X Marks The Treasure

What you will need:

  • Some imagination!
  • White paper
  • Pens and colouring in pencils
  • Paintbrush/Cotton Swab
  • Lemon juice in a bowl (fresh or bottled)
  • Heat tool: a hair dryer will do
The X


  1. Talk about what you might like to be on your treasure map with your child. Explore what will be on an island or in the sea. Sharks? Mermaids? Goblins? Sirens? Octopus? Dangerous forests or erupting volcanoes? The more dramatic, the more exciting!
  2. Depending on the age of your child either get them to draw out their treasure map or with them explaining what they want, you the adult draw it. If they would like, they can colour it in and even add names for parts of the map.
  3. Squeeze your lemon juice into a bowl and with a small paintbrush decide where you would like your X marks the spot to be on your map. You can make this part a game. Either you or your child can draw and X and let it dry without the other person seeing. You can also add the route to actually get to the treasure too as I’m sure many pirates have tried and failed to get to the treasure with lots of traps and obstacles on the way!
  4. Once the lemon has dried it should be for the most part on first glance transparent. The heat tool can now be gotten out, turned on aimed at the map. Slowly you will see parts of your map start to turn brown. If you have done a trail you will need to move your heat tool along the whole trail for it to be revealed. This will also then lead you to your X marks the spot and TA DA you’ll have located the treasure!

The mystery of the hidden treasure is solved! Now to get passed all those obstacles safely… *enter some pirate role playing*

Invisible Ink X Marks the Spot

Suggestion in how to approach this activity.
Why not make an afternoon or morning out of it. If you have any pirate dressing up costumes put those on. If you don’t can you make a makeshift one? For example like tying a scarf around one eye to make an eye patch, tying a handkerchief or scarf around your head like a bandana.

When the Invisible Ink Treasure Map is dried, why not roll it up and tie some ribbon around it. Then you can hide it somewhere and give your children clues how to get to it. After you have discovered the route to the treasure inside the map why not keep the adventure alive and keep role playing! Do you have a climbing frame outside? Make that your ship to escape! Have fun with it, you may be surprised how much you end up enjoying yourself!

Invisible Ink Lemon Trail

The science behind the invisible ink
When you apply lemon juice to paper and it heat up, the applied lemon juice will darken. Lemon juice is a weak acid and when it is put on paper the carbon compounds in the juice are sucked up by the fibres in the paper. This softens the paper fibres. As heat is added the carbon is broken causing the chemical bonds to break down. When the carbon comes into contact with the oxygen in the air is burns. Another word for this is oxidation. The affect being that it will darken. The same process happens when you cut a banana, apple or even avocado up and leave it in contact with the air, they all begin to oxidise and turn brown.

If you don’t have lemon juice, you can create invisible ink with equal amounts of baking soda and water. The same reaction happens when it comes into contact with heat. You can also hold it up to a light and see the invisible ink.

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