I have a question that has just come to my mind : do you have a dip pen ? It is very likely that your grandparents were using this kind of "tool" to write at school. If you don't have Indian ink, you may try coffee (cheap instant coffee powder mixed with a little amount of water) - it is one of the cheapest way to get something close to "bistre" color.

It is 16h35 in Paris, I am wondering if should draw a little pencil doodle for the fun...

Not very likely, my grandma went to school in the 1960s. I'm pretty sure she's always just used ballpoints. I have bought fountain pens before, though. I like the way those look to write, but I feel like they'd be a bit too unruly for art.

Thanks for the tip, that looks like a pretty cool trick. I'll have to get some instant coffee to try it sometime. I have an electric percolator from the 1950s for making coffee, so I don't usually have any instant coffee on-hand unless someone gives me some, or something. Lol