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Food Science Science Fair Project

Lemon Juice Invisible Ink

Lemon Juice Invisible Ink | Science Fair Projects | STEM Projects
Lemon juice can help you create secret messages that are invisible until exposed to heat. When heated, the lemon juice oxidizes and turn brown, revealing the hidden message.


The hypothesis is that by writing a message with lemon juice and exposing it to heat, the carbon compounds in the lemon juice will break down and oxidize, causing the once invisible message to become visible.

Method & Materials

You will use lemon juice as ink to write a message or draw a picture on paper. Then, after it dries, you will heat the paper with a hair dryer to reveal the hidden message.
You will need lemon juice, a small bowl, a q-tip, paper or paper towel, and a hair dryer.


When the secret message was heated up, the hidden message written with lemon juice became visible as it turned brown.

Why do this project?

This science project is interesting because it teaches how a common household item like lemon juice can be used to create invisible ink and how heat can make it become visible.

Also Consider

Experiment variations to consider include using other citrus juices, like lime or orange juice, or experimenting with different heat sources to reveal the message.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related video

Hey there! Here are some awesome videos about this science project that we think you'll really like. They're not only super fun, but they'll also help you learn more about the science behind the project. So sit back, relax, and get ready to have some fun!!
Learn from the Children's Museum of Atlanta how to write a secret message with lemon juice and then reveal it using a hair dryer. If the message is not visible, try revealing it by holding the paper over a candle flame like in the video.
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