If you are having difficulties cleaning the dark residue inside your thermos, try this unusual but effective method.
An unpleasant residue often remains on the walls of a thermos after using it for tea or coffee.
One effective means of restoring the cleanliness of a thermos is denture cleaning tablets.
To get rid of the residue, place one tablet inside the thermos.
One capsule will be enough for half a liter of water.
Place the thermos in the kitchen sink and fill it with boiling water — the solution will start to foam actively, but this is normal, as you have prepared a place for it in advance.
Leave the thermos in this state for at least 2-3 hours, then pour out some of the solution and thoroughly wipe the walls from the inside. A bottle brush is best suited for this.
After that, simply rinse the thermos with warm water, and it will look like new again.
