In any environment chalk is likely to pick up a little moisture from the air. Maybe if it's being stored for a long time it could be a good idea to put it with a pack of silica gell (the little sachets you get in the boxes of new shoes) - which absorb humidity.
Or maybe that could dry the stuff out too much, I don't know.
Next time I get some new shoes I might give it a try.
well with some chalk they have petroleum by-products that will cause some tips to glaze over and they will require scuffing more often........silver cup chalk is from a local company near here in macon ga and it is a pretty good chalk but a little dusty.....on the other hand masters chalk will cause the tip to glaze over a little and will cause you to need to scuff more often........just thought this would of some help.....juston coleman