Science Questions

How does an eraser work ? John, Barr Hill

When you write on a piece of paper with a pencil small particles of graphite (Carbon) which makes up the pencil lead become embedded in the paper matrix. An eraser works by sticking onto the graphite and tugging the particles out of the paper matrix. You cannot erase biro or other pens because the ink isn't made up of discrete particles that can easily be removed. To do so you physically need to remove alayer of paper.

August 2002