Not trying to derail the OP, just trying to learn more....
     In my lovely (cough) sonoran desert home, we've seen RH as low as 2%. (No, that's not a mis-key) I've been told that it's simply not physically possible for it to go any lower than that. We can also see it up in the mid 90% range during monsoon season. 
It makes for amusing wood working conditions. 
It also explains (in part) why I have never bought any raw staves to work on. They might very well be wrecked before I can even unwrap 'em. 
Anybody have a way to maintain humidity for storage, short of a walk in humidor?
---Ford---