Messages With Invisible Ink
Project overview: This is a project that combines chemistry and art. This is a craft project that is a great way to explore science principles of oxidation and thermal decomposition through a fun and creative way!
Materials required:
Lemon juice: (freshly squeezed is best)
Cotton swab or a clean paintbrush (acts as a pen)
White paper
A heat source (light bulb, iron, hair dryer)
Instructions:
To prepare the “ink” squeeze some lemon juice into a small bowl and add a drop or two drops of water to thin it out if needed.
To write the message, dip the cotton swab or paint brush into the juice and write the secret message onto the white paper. Note: don’t worry if it looks like the paper is getting wet because it will disappear once it dries.
Wait until the paper is completely dry. The paper should look blank.
To read the message that you initially wrote, hold the paper near the heat source. If using a lightbulb, hold the paper near but not touching the bulb to avoid burning the paper. If using an iron, set it to a low to medium dry setting and gently iron over the paper.
The heat will cause the lemon juice to oxidize and turn brown faster than the surrounding paper. Therefore, revealing your message!
Explanation:
The lemon juice contains carbon based compounds that when absorbed into the paper will remain invisible once the water evaporates. When heat is applied, the carbon compounds will go through thermal decomposition and oxidize, causing them to brown faster than the surrounding paper. This therefore, creates an invisible difference that reveals the hidden message that was initially written on the paper.
