A stainless steel thermos keeps liquids hot or cold, but it also holds onto strong smells. The odor can build up in the thermos over time if you do not clean it out regularly. Smells can also form if a thermos containing liquid is left in a warm location as bacteria will multiply quickly. The lingering smell of coffee, tea or soup can make the thermos unbearable. Instead of throwing it away, deodorize the thermos immediately to freshen it.
Baking Soda and Water
Rinse the stainless steel thermos with warm water to remove any residue.
Pour 1 tsp. of baking soda into the thermos.
Fill the thermos with warm water. Let it sit for 30 minutes or overnight for best results.
Rinse the thermos with warm water. Add the baking soda and water mixture to the thermos again if the odor remains.
Baking Soda and Vinegar
Add 1 to 2 tbsp. of baking soda to the thermos.
Pour 1 cup of white or apple cider vinegar into the thermos. The vinegar and baking soda will foam. Close the lid tightly.
Shake the stainless steel thermos. Pour the solution into the sink.
Rinse the thermos well with clean water.
Pack crumpled newspapers into the thermos.
Close the lid of the thermos. Let it sit for two to three days to allow the newspapers to absorb the odor.
Remove the crumpled newspapers.
Wash the thermos with warm, soapy water. Rinse it with clean water.