20 Jul 2020
If you think about it deeply, erasers are a largely uncredited marvel – not only did they take into account that humans are essentially bound to make mistakes, they also allow you to experience the joy of correcting your mistakes with no trace of your error (quite unlike reality).
However, have you ever been curious as to how erasers work, so as to allow you to magically wipe out all your pencil marks? I’d take that back though, for it’s not magic, but merely an intelligent use of scientific principles like friction.
Let’s start by looking at what erasers are essentially made of. Erasers are mostly made of rubber (hence the Indian convention of referring to an eraser as a “rubber”), with softeners (like vegetable oil, to make it more flexible) and abrasives (like pumice).
Pencil marks on paper, on the other hand, are left by graphite (an allotrope of carbon) particles which rub off from the pencil and stick to the fibres of paper. So, when you attempt to eliminate a pencil mark by using an eraser, the abrasives’ scratching of the fibres loosens the graphite particles and the particles instead cling to the eraser. However, why do the particles cling to the eraser in the first place?
The answer lies in friction, or the heat that the rubbing of two surfaces creates. When the eraser is rubbed against the paper, the friction produces heat. The heat makes the rubbers in the eraser sticky, allowing the graphite particles to cling onto the eraser and ultimately remove themselves from the paper’s surface fibres.
So, the next time you reach out for that eraser, remember just how powerful Physics can be even in these small, or rather ordinary, moments of everyday!