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Home » Science Experiments for Kids » Chemistry » Lemon Juice Invisible Ink Science Challenge

Lemon Juice Invisible Ink Science Challenge

Modified: Feb 1, 2024 · Published: Jul 2, 2011 by Emma Vanstone · This post may contain affiliate links · 4 Comments

This week, we are playing detective and making secret messages with DIY invisible ink.

You can write messages or draw pictures to send to friends using secret ink and make them appear using a special trick!

(Note: it does require heat to reveal the messages, so do supervise young children )

How to make invisible ink

What you need

  • Half a lemon
  • Water
  • Spoon
  • Bowl
  • Cotton bud
  • White paper
  • Hair dryer

1. Squeeze the lemon into a bowl. Add just ⅔ drops of water to dilute. This is to make it clearer on the paper! Your invisible ink is now ready.

2. Take your invisible pen (your cotton bud) and dip it into the ink. Write or draw your message.

3. Leave to dry.

4. To reveal your message, you need to apply a heat source. Either hold it near a lamp, iron it or place it in the oven. (I found the oven worked best). You must watch it carefully to ensure the paper does not scorch.

5. Admire your message!

The science of invisible ink

Lemon juice oxidises (which means it reacts with oxygen) and turns brown when heated.  

Diluting the lemon juice in water makes it harder to notice the invisible message on the paper.

invisible ink made from limes

Other substances to try

Orange juice

Lime juice

Milk

Vinegar

Fizzy drinks

More fun science for kids

This activity is also part of my Playful Science series, which is full of simple play-based science activities for kids.

Image for a Playful Science series of fun, simple science for kids

Make a magnifying glass, create your own code, and more detective based science experiments.

Red Ted Art also has some great ideas for how to write secret messages!

image of lemon juice based invisible ink

Last Updated on February 1, 2024 by Emma Vanstone

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Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

Comments

  1. Helen R

    July 03, 2011 at 4:48 pm

    This is brill! My toddler is cutting down her nursery days from tomorrow so great to have some simple ideas for educational entertainment!

    Reply
    • Amanda C

      October 02, 2013 at 2:57 pm

      Where does the hair dryer come in at, as a heat source to see or to just dry the paper?

      Reply

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