We use a tube with a so-called EVOH barrier. This is exclusively for MUDMASKY masks. This tube guarantees the freshness of the ingredients (including the antioxidants) for 12 months after opening. MUDMASKY masks are made from natural ingredients, so they will respond to extreme heat or cold. MUDMASKY masks must be stored at room temperature and away from direct sunlight to maximise the life and effectiveness of the product.