The magic pen

The magic pen has a very special ink, which becomes invisible when heated.

Use the pens to write secret messages, treasure maps or love letters. The magic ink becomes completely invisible when exposed to heat. The flame from a lighter works well, but also a warm light bulb, a hairdryer, a cup of hot tea, an iron, or just put the paper on a panel oven.

You can also use the eraser on top of the pen. The heat from the friction will cause the ink to disappear.

It looks like magic. Actually, it's chemistry. Really fancy chemistry.

You conjure up your secret drawings by making the paper really cold. A minute in the freezer does the trick. Or if you want to take it to the next level you can run dry ice or cooling spray.

Frequently asked questions

What paper does it work on? It works on all types of paper!

Won't the paper catch fire? No! The ink disappears at 40°C, while ordinary paper ignites at 233°C.

How cold does it have to be? The ink reappears at around ten degrees below zero, so a round in the freezer works well. But you should be careful about sending secret messages with Posten in the middle of winter.