Erasers work because of friction. ... As the abrasives in your eraser are rubbed against paper, friction produces heat, which helps the rubber become sticky enough to hold onto the graphite particles. As the rubber grabs the graphite particles, small pieces of combined rubber and graphite get left behind.

Why do erasers get hard?

Pencil erasers are made from thick rubber that has the tendency to harden and become brittle when exposed to direct sunlight. Moistening them can make them work again.

How does an eraser rub off what you write?

When you rub an eraser across a pencil mark, the abrasives in the eraser gently scratch the surface fibers of the paper to loosen the graphite particles. The softeners in the eraser help to prevent the paper from tearing. The sticky rubber in the eraser grabs and holds on to the graphite particles.