Erasers, Ratzefummel or Raditze. No matter what we call them, we all remember the erasers of our school days. But what is the scratchy blue side for?
In addition to fountain pens and pencils, there was one item that could not be missing from the primary school equipment: The eraser. Always ready to make small and significant mistakes in the math notebook disappear. The classic eraser has a red and a blue side.
Red erases the pencil from the paper without problems; that’s clear. But the blue side is still a subject of debate today.
Myth or fact: Does the blue side make ink disappear?
In fact, according to the manufacturer Faber Castell, the blue, rough side erases ink from paper. Quartz powder is added to the rubber or plastic that makes up the eraser for this side. This also allows ink to seep further into the form to be erased. At least indirectly.
The rough surface only ensures that the top layer of paper is rubbed off. If you do this too enthusiastically, you’ll quickly erase a small hole in the paper.
How does an eraser work?
When you write with a pencil, a small layer of graphite comes off the lead and sticks to the paper. This is because of the adhesion force. This means that different particles – paper and graphite – attract and stick together. You can find out more about the adhesion force in the video.
This is precisely the force that acts when you run the eraser over the letters. This is because the attraction between rubber and graphite is more significant than between paper and graphite.