ElI5: Why a pen sometimes refuses to write on a specific part of the paper but works perfectly fine everywhere else?

Question

ElI5: Why a pen sometimes refuses to write on a specific part of the paper but works perfectly fine everywhere else?

In: Other

Answer 1

The way a ball point pen works is that the tip has a ball in it (hence the name), and as the ball rolls across the page it picks up ink on the top of the ball then deposits it down on the page as it rolls over. If this ball happens to get stuck, it will slide across the page and not leave any ink, so like any normal person you find a scrap piece of paper and scribble on it to get the ball rolling again. However when you try to write over the area where the pen stopped working in the first place, you’ve already crushed the paper & made it smooth, and that smoothness means that there’s little to no friction to keep the ball rolling, making it difficult to write there.