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

At least two reasons I can think of

For a ball pen: The ball may be dried out. After rolling it a bit, it may work again normally.

Fat (or other dirt) on the paper may be the issue