What has turned out to be a good rule of keeping tobacco stored for me,
is that if I don't know what it is and/or don't want it in my body,
then don't use it. If the blend dries out, I can always re-hydrate it.
You can even do this on the spot, or when you're in a hurry. Fill the
Pipe with the dry tobacco. Cup your hands around the bowl, to form a seal
and exhale 3-4 times into the bowl. The moisture from your breath will
re-hydrate the tobacco. If you have time, place the tobacco in a bowl
and cover it with a towel, moistened with distilled water. Do not let the
towel come into contact with the tobacco. Leave it for a few hours or
overnight, depending upon how moist you want the blend to be.