Each Boveda pack is wrapped in a plastic overwrap to keep them fresh until you're ready to use them. Shelf life of Boveda left in their overwrap is 2 years.
When do you use a 320 gram Boveda? Whenever it fits in your storage container. Boveda will never humidify beyond the RH on the pack, so there’s no such thing as “too much”. You want to think in terms of using at least the minimum because the more you use, the more efficient Boveda works and the longer they last. 60 gram Boveda are commonly used in mason jars and large bags. They can last 6+ months depending on how often the container is opened, you’ll know it’s time to replace when the entire Boveda begins turning hard.
Each Boveda consists of a specially prepared saturated solution of pure water and natural salt. This saturated solution is contained within a water-vapor permeable “reverse osmosis” membrane. Within a closed desktop humidor Boveda maintains a predetermined level of (RH) by releasing or absorbing purified water-vapor, as needed, through the membrane.
Boveda provides the cleanest and most purified humidity of all other products available on the market today.