Waterproof pen recommendations?

Hi everyone, yesterday I got the worst email from Postcrossing that one of my postcards was stuck due to the ID number not there or obscured. I felt so bad! Postcrossing was able to help though and my postcard was registered thankfully! But now I’m worried that this might be because the gel pens I use smudge so I want to get some new waterproof pens!

Looking for your suggestions or out there is another thread about this somewhere let me know.


4 posts were merged into an existing topic: Your favorite pen to write postcards?