For those that want an erasable pen, there's one brand out called Frixion pens
They're erasable through the "friction" (otherwise, heat) and the ink comes back through cold.
I've used them on newsprint, and they don't rip the paper, smudge, or anything negative. It's just blank space again.
You don't need to erase for a long time, just a few good rubbings is enough. It's almost magical to watch!