Make an invisible ink!
Make invisible ink with lemon juice and a cotton swab, write secret messages, then reveal them safely by warming the paper with adult help.
Step-by-step guide to make invisible ink
Step 1
Put a tea towel or scrap paper on your table to protect it.
Step 2
Place one sheet of white paper on the protected spot.
Step 3
Pour about one teaspoon of lemon juice into the small bowl using the spoon.
Step 4
Dip the tip of a cotton swab into the lemon juice.
Step 5
Tap the swab gently on the side of the bowl to remove extra juice.
Step 6
Write a secret message or drawing on the paper using the lemon soaked cotton swab.
Step 7
Let the paper dry completely until it feels dry to the touch.
Step 8
Ask an adult to slowly warm the paper with a hair dryer or hold it near a warm light bulb until the message appears.
Step 9
Look closely as your hidden message turns brown and becomes visible.
Step 10
Throw away used swabs wash your hands and tidy your workspace.
Step 11
Share your finished creation on DIY.org
Final steps
You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!
Help!?
What can I use instead of lemon juice or cotton swabs if I can't find them?
If you don't have lemon juice, use milk or diluted vinegar in the small bowl and, if no cotton swabs are available, use a clean paintbrush or toothpick to write on the white paper.
My secret message didn't appear when I warmed the paper—what went wrong?
Make sure you used enough lemon in the small bowl (step 3), let the paper dry completely (step 7) and avoid smearing by tapping the swab on the bowl edge (step 5) before asking an adult to warm the dry paper slowly with a hair dryer or warm light bulb (step 8).
How can I change the activity for different ages?
For preschoolers, have them dip the cotton swab (step 4) and make big dots on the paper while you hold it, for elementary kids encourage full secret sentences in step 6, and for older kids use a fine paintbrush or create coded messages to reveal after heating.
How can we extend or personalize our invisible-ink project?
Use stencils or stamps during step 6 to create shaped secret messages, decorate the paper with markers and stickers after the hidden message appears (step 9), and turn it into a multi-clue treasure hunt to share on DIY.org (step 11).
Watch videos on how to make invisible ink
Make DIY Invisible Ink! Neat Chemistry Experiment to make Science Fun!
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Facts about safe chemistry experiments for kids
✉️ You can write secret messages with a cotton swab dipped in lemon juice; once the paper dries it looks blank.
🔬 Invisible inks have been used for centuries by soldiers, messengers, and spies to hide secret notes.
🍋 Lemon juice contains citric acid and tiny sugars that stay invisible when dry but brown when heated — that's how lemon invisible ink works.
🧪 This activity is a fun way to see basic chemistry in action: heat-triggered color change and oxidation at work.
🔥 With adult help, gently warming the paper (an iron or light bulb) makes the hidden writing appear — never use an open flame alone.
How do you make invisible ink with lemon juice and reveal the message?
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