How to clean coffee stains from stainless steel thermos

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Coffee thermoses are great ways to keep your favorite pick-me-up hot(or cold) throughout the day. But when your coffee thermos begins to smell like old coffee, it’s time to give it a thorough cleaning!

The shape of coffee thermoses makes it kind of tricky to clean well, but these methods make use of some clever chemistry to thoroughly clean the thermos without much hassle.

Everyday cleaning for your coffee thermos

Coffee rinses out fairly easily, so being diligent about rinsing your thermos with warm water right after using it should be sufficient to get it fresh for the next day.

For a more thorough cleaning, here’s what you’ll need:

• dish soap
• warm water
• a bottle scrubber

Here’s what to do:

1. Rinse the thermos with warm water.
2. Put a drop of dish soap on the bottle scrubber, wet it with some water, and scrub the inside of your thermos.
3. Rinse out all of the soap

Just following these steps every day should keep your thermos nice and fresh for every next batch of coffee.

How to remove coffee stains from a thermos

Did you forget to clean a thermos for a long time and are now left with a thick coffee residue that’s impossible to reach?

You can use some nifty chemistry tricks using household materials to get even the toughest coffee stains out of your stainless steel thermos.

Baking soda and vinegar method

What you’ll need:

• White vinegar(1/2 cup)
• Baking soda(1 tbsp)
• Warm water
• A bottle brush

What to do:

1. Pour the vinegar into your thermos
2. Sprinkle the baking soda over the vinegar. Do this over a sink in case some of the mixture spills out, as baking soda and vinegar react very strongly and produce lots of bubbles
3. Fill the thermos with warm water up to the neck. Leave a little room as the baking soda and vinegar reaction may still occur
4. Let the thermos sit for 10 minutes as the chemical mixture looses the stains
5. Use a bottle brush to scrub the inside of your thermos
6. Empty the thermos and rinse 2 to 3 times with warm water
7. Keep rinsing until the vinegar smell is gone
8. Place on a dishrack to air-dry

Salt and ice method

You can also use a combination of salt and ice to loosen up coffee stains.

What you’ll need:

• Crushed ice cubes
• 2 tablespoons of coarse salt

What to do:

1. Add crushed ice to your thermos about 1/3 of the way
2. Sprinkle salt over the ice
3. Place the cap on the thermos and shake it vigorously as if your life depended on it. The salt and ice act as an abrasive that remove the coffee stains from your thermos without doing any damage to the steel walls
4. Throw out the ice and salt
5. Rinse the thermos a few times and let it air dry

Note: The salt and ice method works great for removing any stuck residue, but it will not be as effective as removing lingering smells.

Dishwashing powder method

What you’ll need:

• 1 scoop dishwashing powder(not liquid)
• Warm water

What to do:

1. Add dishwashing powder to your thermos
2. Fill it up with warm water about halfway
3. Place the cap on the thermos and give it a good shake
4. Fill up the thermos all the way with water
5. Let it sit for a few hours to loosen the stains
6. Empty out some of the liquid and use a bottle brush to scrub the insides
7. Rinse out the thermos a few times and let it air dry

Denture tablets method

Denture tablets are like toothpaste for dentures and they’re very effective at removing food stains from surfaces.

What you’ll need:

• 1 denture tablet
• Warm water

What to do:

1. Fill up your thermos about halfway with warm water
2. Add a denture tablet. Do this over the sink to prevent any overflows
3. Let the thermos be for 30 to 40 minutes to let the chemical reaction do its thing
4. Use a bottle brush to scrub the insides
5. Rinse out the thermos a few times and let it air dry

Related: How to clean a stainless steel coffee pot

Conclusion

Cleaning a coffee thermos can be a pain, so it’s best to be proactive and rinse your thermos well after each use to prevent any build-up in the first place.

If your thermos is dishwasher-safe, just place it in the dishwasher with the rest of your dishes every day and you won’t have to worry about it!

If all else fails, maybe it’s time to get a new coffee thermos!

Frequently asked questions

How do you get the coffee taste out of a thermos?

Dishwashing powder does a very good job of getting unwanted tastes out of your utensils.

How do you get the coffee smell out of a thermos?

Vinegar and baking soda is the best way to remove any lingering coffee taste out of your thermos. Vinegar is very overpowering so it does away with other aromas very well. Just rinse the thermos out after adding baking soda and vinegar until the vinegar smell is also gone.

Shab is the Chief Caffeine Officer at Coffee Brewster. When he's not weighing out coffee beans for his next brew, you can find him writing about his passion: coffee.