Clairefontaine paper has a clay coating that makes it hard and smooth, but causes wet inks to dry slowly and remain prone to smudging. With the right combinatio

Clairefontaine paper has a clay coating that makes it hard and smooth, but causes wet inks to dry slowly and remain prone to smudging. With the right combination of fountain pen and ink, particles of the clay will be dislodged and float up into the pen, eventually clogging the feed. I had one pen+ink combination that would clog up after writing about 2/3 of a page on Clairefontaine paper. Rhodia paper is made by the same people but has less clay coating, so these problems are a bit less. Still, neither takes pencil well, so I would just use ballpoint or a drier gel on either.