Invisible Ink Techniques for Card Marking – A Closer Look

Invisible Ink Techniques for Card Marking: A Closer Look

Card marking is a form steganography where invisible marks are written onto the surface of documents or other objects. These marks can be made more visible using heat or UV light. The invisible liquid used to write the message can be applied to the writing surface using a special pen or stamp, a fountain pen, a toothpick, a cotton swab or another similar item. This ink then dries.

The message is revealed by applying a developer after the invisible ink has been written on the paper. This may be a simple solution such as lemon juice, or it can be more complex chemical reagents. The most important point in using invisible ink is that the writer must be careful not to arouse suspicion. Telltale signs can alert a censor, such as scratches caused by a pen, roughness in the paper or a difference in reflectivity due to the ink.

Invisible ink can be used to write a secret note on cards. It is easy to make, and you can use ingredients that are probably already in your house. You will need a pen and a shallow bowl or dish, white paper, and an acidic liquid such as vinegar, lemon juice or milk to make your own invisible pens. You will also require Q-tips, and a heat source such as an iron or radiator.