[privong]

> If you turned in an assignment written in pencil, it was legit for the teacher to use their eraser and give you an F for turning in empty paper. (They never did this but threatened it a lot).

I find this slightly amusing/ironic because many (most?) fountain pen inks are not waterproof. I had a sheet of paper that was full of (fountain pen written) writing on my desk when I spilled a glass of water -- after the paper dried there was hardly any evidence that there had been writing on the paper. I know that's not the parent's point, but something turned in that was written with a fountain pen would be easier to remove: a teacher would just need to dunk the paper in water!

[michaelt]

> many (most?) fountain pen inks are not waterproof.

I assumed this was for child friendliness - you just know kids are going to get ink on their fingers etc while changing cartridges from time to time.

[privong]

It could partly be that, but I've generally read that the default inks are not waterproof.

I was curious about this so I just did a quick non-scientific perusal of one fountain pen enthusiast shop's offerings. It shows 118 of the ink bottles they sell are water-resistant ink while 935 are not (looking at the Yes/No filter counts for "Water-resistant" at https://www.gouletpens.com/collections/bottled-ink). There's a lot of duplicate inks that can be purchased in multiple bottle sizes, but picking the three most represented bottle volumes (20ml, 30ml, and 50ml) it drops to 24 water-resistant inks and 578 inks that are not water-resistant.

The above includes a lot of "interesting" colors; further restricting to black ink only ends up with 3 that are water-resistant and 26 that are not.

[randcraw]

Apparently the inks used in antiquity were not waterproof either. Even though vellum or high quality parchment could last several centuries (if not eaten by moths or other bugs), a single slip of a beverage could erase an entire scroll. Perhaps that's a primary reason that 90% of the works written before the fall of Rome have been lost.

[kqr]

Indeed, pencil is one of the best writing implements for archival purposes. As long as one doens't deliberately try to get the graphite off, it'll probably stay on.