That musty odor....

[profholt82]

I second the dryer sheet recommendation. I've done this with books, record sleeves and cardboard video game boxes numerous times over the years to great success, so I see no reason it wouldn't work for baseball cards.

Edit: whenever I've done the dryer sheet fix, it has been because the item has stunk of cigarettes, not really a mustiness. It's the same premise though, but I just thought I should point that out.