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Science Sundays: How To Make Invisible Ink

Invisible Ink
Posted at 11:24 AM, Feb 15, 2023
and last updated 2023-02-15 14:24:05-05

(KERO) — People have seen it in spy movies, secret messages written through invisible ink. As it turns out, the average person may have all the ingredients needed to make their own invisible ink right in their own kitchen.

To make the ink, they would need a lemon, a bowl, water, a paintbrush or cotton swab, paper, and a source of heat. First, they should cut the lemon in half and squeeze the juice out into a bowl or cup b before adding some water to the cup and mix.

Once they have their invisible ink, it's time to write the message.

To write the message, the person must take their piece of paper and their writing tool and write their message before leaving it to dry completely.

To make the message appear once the message is dry, a source of heat is needed. Possible heat sources include a hairdryer, an oven, or an iron. Use the source to heat the secret message before watching it appear.

So how does the invisible ink work? Well, lemon juice has carbon compounds and at room temperature, they do not have any color, therefore the ink is invisible. When heat is applied to these compounds, it breaks and releases the carbon, leaving it to come in contact with the air. The process of oxidation occurs, turning the letters brown and revealing the message.