After using the hotpack I reactivated it as instructed, but the pack does noy stay in the "unused" state.
It immediately falls back to the "used" state, and in the proces it generates the heat as expected.
If this is normal, than you have to reactivate it just before using it. But since that is with boiling water, it's not safe!
VITILITY: Thank you for your reaction. You probably don't reactivate it correctly. You should reactivate it with boiling water. Leave it in boiling water untill all the 'white' fluid has disappeared and the fluid is completey clear and liquid again. Then leave it to cool. You can reuse it whenever you want