Mjölnir, the hammer of the thunder god Thor, is considered a powerful weapon and a divine instrument for blessing and protection in ceremonies such as births or weddings in Norse mythology. The longevity of the food-safe seal is ensured by proper care: The cup should only be cleaned by hand with lukewarm water, never soaked, and never washed in the dishwasher. Hot or highly acidic drinks should also be avoided, as these can damage the protective layer. Occasionally rubbing the outside with vegetable oil will also maintain the suppleness of the natural material.