Cleaning a thermos bottle

Add 2 spoons of bleach to a thermos filled with water and a little dishwashing soap. Shake and let rest 5 minutes. Shake again and rinse with warm water. If not satisfied, add uncooked rice to the soapy water, then shake again real good. The walls will be scoured perfectly. If you don't it use for a long period, put a piece of sugar inside. It will absorb the musty smells.