I've just noticed this thread and I have to challenge the idea that hexe can be left for years and will function perfectly. It will absorb moisture over time and while it will still burn when damp, it is more difficult to light and puts out less heat, presumably because of the energy required to drive off the moisture content. If it gets really damp it will flake and crumble.

You are probably safe enough with it in a dry, warm climate, but here in England, it is necessary to store it rather carefully.