How to Clean a Thermos – A Blazing Small Tip

When it comes to maintaining and cleaning a thermos, it actually requires a different approach than your standard water bottle. It is uniquely constructed and uses special materials, materials that are not exactly common in kitchen wares. With that in mind, I’ve made a detailed guideline on how to properly clean your thermos. Check out the guideline below for the variety of ways on how to clean a thermos.

Cleaning Materials that You Will Need

  • Dishwashing Liquid
  • Baking Soda
  • White Vinegar
  • Bottle Brush
  • Rice
  • Denture or Antacid Tablets
  • Salt
  • Ice
  • Water

Cleaning Thermos Methods

There are 4 different ways to clean a thermos: Standard Method - This method uses casual dishwashing liquid and water to clean up a thermos; BAKEGAR Method - this method uses baking soda and vinegar to clean a thermos; thirdly, Ice and salt can help the job done; lastly, Dental/Antacid Tablet Cleaning Method. Now, let's go deeper into how we do it:

#1. Standard Method – Dishwashing Liquid and Water

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  • Step 1:  The simplest method for standard cleaning is to use a few drops of dishwashing liquid and water. First, you need to prepare diswashing liquid and fresh water.
  • Step 2: Pour a couple ounces of dishwashing liquid into the thermos and add water. 
  • Step 3: Attach the top of the thermos and close it shut. 
  • Step 4: Shake the bottle vigorously. To be honest, I really enjoy this step 😀
  • Step 5: Pour the liquid solution out of the bottle. 
  • Step 6: Rinse thoroughly. 

#2. BAKEGAR Method - Baking Soda and Vinegar Cleaning Method

In the instance where there are visible stains inside or on the bottom of your thermos, a water and dishwasher approach might not be enough. This is where you bring in some unique cleaning methods onto the table.

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  • Step 1: Pour in about half a cup of white vinegar into your thermos.
  • Step 2: Pour one tablespoon of baking soda. The mixture will cause a chemical reaction and the vinegar and baking soda will start to froth.
  • Step 3: The baking soda and vinegar concoction is a known bacterium and germ-killing mixture. This step, you will sit down and be calm 😀 Enjoy it!
  • Step 4: Once the froth starts to subside, fill the thermos with hot water all the way to the top. This helps distribute the vinegar and baking soda mixture evenly throughout the interior of the thermos.
  • Step 5: Let it soak for about 10 minutes. Do not put the cap on during this period.
  • Step 6: Take your bottle brush and scrub the interior of the thermos with the cleaning solution.
  • Step 7: Pour out the mixture and rinse the interior with hot water, as much as possible until all traces of the vinegar and baking soda mixture is gone.
  • Step 8: Dry it exterior with a towel and let it air dry. 

#3. Salt and Ice Cleaning Method

This is another method on how to clean a thermos which uses simple and easy to find household items such as salt and ice.

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  • Step 1: Take your ice, preferably crushed or small bits of ice, and fill the thermos up to a quarter full with it.
  • Step 2: Take a couple spoonful of salt (2 to 3 spoonful) and pour it into the thermos with the crushed ice.
  • Step 3: Close the lid on the thermos and shake it vigorously. Any method includes its own interesting part.
  • Step 4: The combination of hard ice, cold temperature, and jagged salt will scrape away at stains and grime inside the thermos.
  • Step 5: Remove the lid on the thermos and pour out the ice and salt mixture.
  • Step 6: Rinse the thermos using warm water and make sure that the interior is completely free of salt.
  • Step 7: Let it air dry.

I actually prefer this method as salt and ice are all-natural cleaning solutions and are perfectly safe, health-wise.

#4. Denture or Antacid Tablet Cleaning Method

Another easy alternative to cleaning the interior of your thermos is by using denture or antacid tablets. These tablets can be bought over the counter from your local pharmacy. The reason for this inclusion here is due to the fact that these kinds of tablets contain sodium bicarbonate as an active ingredient.

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What is sodium bicarbonate? It’s basically baking soda which is a great cleaning chemical. Another reason is that since denture or antacid tablets are designed to clean things you put in your mouth they are also perfectly safe. They have an anti-bacterial effect which sterilizes the thermos.

  • Step 1: A pack of antacid tablets is quite affordable and you will only need a couple which means you will have some extra for future use.
  • Step 2: Pour warm or hot water into your flask. Fill it up to the half-way point. The hotter the temperature the looser the stains will become. Leave the thermos with hot water for a couple of minutes.
  • Step 3: Shake the water around the thermos to make sure the interior is thoroughly wet. This will make sure that the tablets will sterilize the entirety of the interior.
  • Step 4: Take one or two denture or antacid tablets and drop them into the thermos with hot water. The chemical reaction will start immediately and you will find the content to foam up. Do not put the lid on the thermos.
  • Step 5: Leave the thermos and the solution to dissolve. It should take around 30 minutes for the solution to steadily diminish.
  • Step 6: Once the foam has subsided, pour out the solution and rinse with water. Brush the interior with a bottle brush to fully remove leftover residue.
  • Step 7: Let the thermos to air dry. Do not put the cap yet while the interior is still wet as it will cause bacteria to develop.

Additional Tips for Taking Care of your Thermos

As I have stated earlier, a thermos will require a different approach when it comes to the cleaning process. What is the effect on most kitchenware will not be or might even damage the integrity of a thermos? Below is a guideline on what to do and not do when cleaning your thermos.

Never put your thermos in a dishwasher!

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Do not submerge your thermos completely underwater. Water might seep inside the small linings in the insulation which would cause damage over time.

Never use bleach to clean the thermos!

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Bleach can degrade the steel welds inside. If you will be storing the thermos during the summer, I suggest you place a clove inside to prevent the moldy smell from developing. An alternative to clove is a teaspoon of salt.


Final Thoughts

Follow the guidelines and tips above to ensure that your thermos remains clean and in good condition. Also, having a top-quality thermos will ensure longevity and safety. If you have other effective thermos cleaning techniques you would like to share then please feel free to use the comment section below.

Did you find this article helpful? Share it with your friends! Have a nice day, mate!

Kevin Smith

About the Author

Kevin Smith

Ahoy there! The name’s Kevin Smith, the proprietor of this little travel and outdoors blog. The outdoors has always been a passion of mine since I was a kid as my parents were avid campers themselves. They taught me everything I know when it comes to camping, hiking etc. and I would like to do my part by imparting my know-how to like-minded individuals who enjoy the same hobby as me. I started this website in the hopes of helping other people when it comes to answering questions, giving tips and recommendations focusing on the camping niche. Along with some close friends of mine, we are here to help you make the most out of your outdoor experience. Enjoy your stay and enjoy the wild side!

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