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

I think it is usually fat. The paper was touched by (your?) fingers (they are always a bit fat; that is where fingerprints come from). The fat is slippery and the ball won’t roll.