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6 Ways to Remove Coffee Stains from Stainless Steel Thermos

Do you want to know how to remove coffee stains from metal thermos? If YES, here are 6 easy ways to remove coffee stains from stainless steel thermos.

Stainless Steel Thermos is an ideal choice for warm and cold drinks alike because these containers are able to maintain drink temperature for an extended period of time. For instance, if you brew yourself a hot coffee, you can pour it into the flask and enjoy it at its original temperature for around 6 – 24 hours.

Pros and Cons of Using a Metal Thermos

Stainless steel thermos comes in handy if you are planning on hiking or you are going on a long journey, because all you need to do is prepare your drink, pour it into the flask, secure it and then drink it throughout the day. These flasks could really save the day if it’s cold and you need something to warm your bones or if you end up in the wilderness and you need something to keep you going.

Stainless steel thermos is also really helpful for the long-distance traveller who doesn’t want to pay £4 or more for a hot drink at the train station. If you buy a flask then you can prepare your drink in the morning, pop it in your bag and enjoy it throughout the day.

But there is one disadvantage, washing a thermos is a bit more complicated than washing a coffee mug. Due to its specific shape and design, a coffee thermos can be daunting to clean. Have it in mind that for some items, running it through the dishwasher just won’t cut it, so you need to get creative.

If you find that regular cleaning and scrubbing with soapy water still leaves crud at the bottom of your coffee thermos, here are a few tried and tested ways to get rid of stains and smell from your precious coffee container. Below are few methods to use.

6 Ways to Remove Coffee Stains from Stainless Steel Thermos

1. Baking Soda and Vinegar

A white vinegar and baking soda solution can help you get rid of any stains your thermos has picked up. Use a variation of this recipe to clean your thermos;

  • First pour the vinegar into your thermos and dump in one or two tablespoons of baking soda depending on how many cups your flask holds. Vigorously shake the thermos with the baking soda and vinegar cleaner inside, holding it over the sink in case the solution foams over. Do not place the cap on the spout.
  • Immediately the foam from the mixture settles down, pour hot water into the flask to fill it up. Then allow the cleaning solution to do its work for approximately ten minutes. To ensure you get every stain and to make the process easier, scrub the inside of the thermos with a bottle brush that is designed to reach those tight surfaces that you cannot get to by hand.
  • At this point, pour out the mixture and rinse with hot water a few times, until it no longer smells of vinegar. Carefully set the thermos to dry and let it air dry the rest of the way. This is not only the best way to clean a coffee thermos but is also perfect for a coffee maker or your favourite water bottle.

2. Use Ice and Salt

Although it might not sound like a suitable solution to Coffee stain problems, but it really does work. Just make sure your thermos is empty and then fill it a quarter of the way with crushed ice cubes. Pour in two to three big spoonful of salt.

It works best if you use larger grain salt, such as sea salt or coarse-ground salt. Then screw the lid on your thermos and shake vigorously. The coarse salt and hard shards of ice will scrape away stains that build up on the metal.

Shake it until you feel the ice and salt have done their job. Then pour out the mixture and fill the flask with warm water. Swirl it around to loosen any leftover debris and pour it out. Rinse the bottle a couple of times to remove all traces of the salt and then leave it to dry.

3. Use Denture Tablets

One of the main ingredients in denture cleaner tablets is sodium bicarbonate, otherwise known as baking soda. Denture cleaning tablets are also very safe to use on your thermos, as they are made to clean an object that goes in the mouth.

Start by pouring boiling water into your thermos to the halfway mark. Calmly let it sit for a few minutes to loosen the stains and other residue. Shake the thermos vigorously, so every part of the interior is wet. Drop in one or two denture cleaner tablets.

Immediately, the water will start to bubble and foam, so hold your thermos over the sink. Leave the cap off. Let the flask sit for about half an hour and then pour out the mixture. Rinse the container a few times with fresh water and then leave it to dry.

4. Use Lemon Juice

Note that this descaling solution for thermos is also one of the best ways to get rid of Coffee stains. Normally, thermos or appliances you use every day can quickly accumulate build up and stains. Leveraging a natural descaling solution like lemon juice is an easy and safe way to wash away this dirt.

Start by mixing equal parts of lemon juice and water and pour it into your thermos. Let it settle for at least five minutes and scrub with a bottle brush or sponge. Pour out the mixture and then rinse it a few times to get rid of the lemon scent. This cleaning solution is also perfect for your coffee pot.

5. Use Dishwasher Powder

Note that dishwater powder is a powerful cleaning agent that can remove coffee stains and a variety of other stains, as well. Have it in mind that using a powder is more effective than a liquid because it is abrasive and can scrape at stains. For this cleaning method, you need one tablespoon of powder per quart that your thermos can hold.

Just pour the dishwasher powder into your thermos and add some hot water, but do not fill it to the top. Place the lid on your thermos and shake for a few seconds.

Take off the lid and fill it to the brink with water. Place it somewhere and leave it overnight with the lid off. In the morning, pour about half of the solution out and scrub the inside with a bottle brush. Empty and rinse a few times before leaving it to air dry.

6. Using Hydrogen Peroxide

Hydrogen peroxide can be used instead of vinegar in the baking soda and vinegar cleaning solution. Peroxide is also the main ingredient in a homemade antibacterial spray so you know it will sanitize the flask at the same time it cleans it.

Although hydrogen peroxide certainly works on coffee stains, it is particularly useful for food thermoses. Nonetheless, if you use hydrogen peroxide to clean your flask, be sure to rinse it thoroughly after cleaning. To be safe, you may want to give it a quick clean with water and dishwashing liquid before using it.


To prevent coffee stains, it is advisable you rinse your thermos as soon as you can after using. Protracted stay of Coffee remains what causes the stains and smells you want to get rid of. Anything you use every day can quickly develop stains, and this is true of your thermoses, coffee cups, and flasks.

So, instead of getting rid of your favourite things, you can remove coffee stains from stainless steel thermos, get hard water stains off and clean other items using cheap, accessible, and safe ingredients.