How to See Invisible Ink With Glasses

Since centuries, invisible ink has been used to transmit secret messages. For example, spies and clandestine lovers have written letters that would be unreadable to anyone else until they were read by someone who knew how to decode the message.

Many different substances can be used to create invisible ink. They are often able to be seen only after being exposed to some kind of light or chemical.

Some of these invisible pens are only visible in certain conditions, like when heated or exposed ultraviolet light. Others are only visible under a specific wavelength of infrared light.

Some inks are only visible with special glasses which block certain wavelengths. This is particularly useful when creating barcodes with infrared ink (IR), which is difficult to read with the naked eye.

The easiest way to see invisible ink is with glasses that block a particular range of wavelengths, such as UV or infrared ink. These glasses can be found at your local pharmacy or online.

Write Your Messages With Invisible Ink

Investigate how certain substances could be used as invisible pens. Change the conditions they are under, such as when they are heated, treated with chemicals or exposed to ultraviolet or infrared light, and you may be able to reveal a message that was hidden for a long time.