• Question: what makes a friction pen rub out ink

    Asked by Ahmed #21 to Nicholas on 15 Nov 2015.
    • Photo: Nicholas Pearce

      Nicholas Pearce answered on 15 Nov 2015:

      Hey,

      When you write, friction from the rough surface of the paper rolls the ball at the tip of the pen around. The ink sticks to the paper much better than to the ball at the tip of the pen and leaves a mark behind. The rolling of the ball brings new ink to the end of the pen, so you can continue to write.
      This is a beautifully filmed video, showing you in slow motion what happens:

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