How do I know when my Boveda pack has stopped working?

Boveda packs contain water and salt, which controls the RH balance. When they dry out the water and salt crystalise. The pack will feel hard inside, usually this begins around the edges first while the middle remains soft. At this point the pack can still be used, although it will not give the same RH humidity. This is the time to keep an eye on it. When the salt and water fully crystalise the pack will be completely hard and no longer keep your CBD at optimum percentage RH storage conditions.