Are you really that helpless?
Noflynomore, It really pi$$es me off to see this sort of comment on a public forum. Not only is it extremely rude, but it can only discourage those less experienced amongst us (and that includes me at 65) from asking perfectly legitimate questions on perhaps more important topics concerning safety, for fear of ridicule. There is no such thing as a "stupid" question.
Anyway, to the original OP, apart from the pens, I found Nail Polish Remover Pads (available from most Chemists) useful to clean the charts effectively after use, and easy to carry in your flight bag without fear of spillage.