How to Make Disappearing Ink Reappear

Written by maxfield carroll | 13/05/2017
How to Make Disappearing Ink Reappear
You can't always see ink like this. (bottle of ink image by Alfonso d"Agostino from Fotolia.com)

Imagine that you have received a note from a friend, or perhaps, intercepted a message from an enemy. But the paper appears to be blank. Well, fear not. If the message is written in disappearing ink, a few simple steps can reveal the hidden communication.

Things you need

  • Heat source

  • Juice

  • Vinegar

  • Cotton swab

  • Brush

  • Sponge

Apply heat to the paper. Use a 100 watt light bulb, an iron or a blow dryer. If the disappearing ink is an acidic or organic substance such as lemon juice or milk, the paper will burn at a different rate than the ink, revealing the spots where the secret ink lies.

Apply a chemical reagent such as lemon or grape juice with a brush, sponge or cotton swab. Experiment on a small portion of the page to see which reagent works best. For example, if the invisible ink is a baking soda solution, acidic grape juice will react with the sodium bicarbonate, revealing the message in a different colour. You can try apple juice, lemon juice, vinegar, grape juice, white wine and many other acids.

Rub salt into the disappearing ink. Wait a minute and then brush the salt off the paper. To reveal the message, write over the page with a wax crayon.

Warnings

  • When heating the page, be careful not to ignite the paper. Do not use a halogen lamp because there is a greater fire hazard.

Tips and Warnings

  • When heating the page, be careful not to ignite the paper. Do not use a halogen lamp because there is a greater fire hazard.

Things you need

  • Heat source
  • Juice
  • Vinegar
  • Cotton swab
  • Brush
  • Sponge

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