cart Shopping Cart cart(0)

Lemon Juice Christmas Cards - The invisible ink experiment

You will need:

  • Lemon juice, bowl, paper, a cotton tip and some pens
  • A spotlight ​or hair dryer

    Materials for lemon juice writing
    Materials for lemon juice writing



  1. Squeeze some lemon juice into a bowl.

    Putting lemon juice into the bowl
    Putting lemon juice into the bowl 
  2. Use a cotton tip to paint your lemon juice onto your Christmas card. This lemon juice needs to dry so don't use too much!

    Using a cotton tip to pain lemon juice onto paper
    Using a cotton tip with the lemon juice onto paper
  3. Turn on a spotlight or hairdryer and allow it the paper to heat up (SAFETY: don't use an open flame like a candle).
  4. Place your paper over the spotlight or hair dryer, allowing the paper to heat up.

    Lemon juice writing and hair dryer
    Heating up the lemon juice with a hair dryer 
  5. Move you paper over the heat source until the lemon juice turns brown in colour.

    Lemon juice on paper after heating
    Lemon juice on paper after heating 
  6. Stop before the paper begins to burn!

    Back to kitchen chemistry experiments

    Back to heat experiments

    Be Amazing Book Front Cover; Ben Newsome, teacher & founder of Fizzics Education. Be Amazing -how to teach science the way primary kids love

    Be Amazing!
    How to teach science, the way primary kids love

    Read more about Be Amazing
    Want more ideas for teaching science?

    Subscribe to the FizzicsEd Podcast!

    Listen to FizzicsEd on Apple Podcasts

    FizzicsEd podcast available on Stitcher

    Back to Kitchen Chemistry science experiments

    Back to heat experiments

Why Does This Happen?

This is the classic 'invisible ink' experiment. Lemon juice is acidic and contains sugar. 
The acid from the lemon juice affects the paper, effectively weakening the paper structure. Adding heat to the paper causes the acid affected paper to burn first. Additionally sugar will form caramel when heated, this is present in small quantities within the lemon juice. 

  • Try other fruit juices - which work best? 
  • Also try other weak acids; does this work as well? 
  • What will happen if you add extra sugar to your painting solution?
Join our newsletter for more science teaching thoughts & ideas

Join the Fizzics newsletter

  • A teacher favourite :)
  • Proclaim your love of chemistry!

    science kits for sale
mixing solutions

Marvelous mixtures school science workshop

  • Learn about suspensions, colloids & more
  • Discover mixture separation techniques
read morebook now

>100 Free Science Experiments on this site!

Coloured shadows
  • Experiments to colour your class!
  • Easy & fun
read more
skeleton and student
  • Make fake blood & more!
  • Biology made simple
read more
electricity experiments
  • Circuit science for kids
  • Cheap materials found easily
read more
Vortex rings made with fog
  • Experiments using Newton's Laws
  • Step by step science
read more

School Science Visits: 

  • Highly engaging & curriculum-linked
  • Additional Teacher Support Resources
  • Professional visits in-class or via video conference
  • Both Primary School & High School science incursions
Call 1300 856 828 or use this form to discuss or make a show booking for your school!

Love Science?

Signup to our fortnightly email! Learn more

Contact us

1300 856 828

Unit 10/55 Fourth Ave
Blacktown, NSW 2148, Australia
facebook-icon Apple Podcast Icon  twitter-icon
linkedin-icon youtube-icon   pinterest-icon