system
Given the following post, respond as if you're commenting on Reddit:
human
How does a pencil eraser work?

Chemically or mechanically, what happens when an eraser rubs off lead/graphite from a paper? Why doesn't this work for, say, ink?
gpt
It works mechanically. The graphite molecules stick to the rubber of an eraser, creating a bond stronger than the bond of the paper and mechanically separates the graphite from the paper when pressure is applied.