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Cleaning a Stainless Steel Thermos

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Tea and coffee are common beverages kept in a thermos. Both can leave stains inside. This is a page about cleaning a stainless steel thermos.


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April 21, 2009

I have a stainless steel thermos and had always cleaned it with Crystal dish soap and had no problem. I was always using tea, however this time I used liquid dish soap. The man used coffee with the cream in it and the coffee came out tasting sour. What happened?



November 26, 20091 found this helpful
Best Answer

I wanted to be the third to say thanks for the tip on hydrogen peroxide and baking soda. I cleaned both a thermos and a baking pan (cookie sheet) that had Thanksgiving sweet potatoes residue stuck on it -- I didn't want to scrape off the non-stick on the pan, and the mixture worked great.

Do mix the hydrogen peroxide and baking soda in a thermos or glass or some other container so you can shake it and mix everything before pouring in on the baking pan. Otherwise clumps of baking soda might block the solution from cleaning parts of the pan.

Back to the thermos cleaning: I also experimented with how much hydrogen peroxide is needed. I found that about 1"+ of hydrogen peroxide, and then regular tap water combined with about 1/5 box of baking soda set over night would clean a moderately coffee-stained thermos just fine. I did what others suggested, and put the lid on and shake it first, and then remove the lid. I let the thermos sit overnight, and dumped the floaters and any undisolved baking soda in the toilet. It might not have clogged the sink, but I didn't want to take a chance.


Thanks again to those who gave this initial tip!

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October 17, 20101 found this helpful
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Went online this morning to ask if it was safe to clean a stainless steel thermos using bleach. What I got was suggestions to use hydrogen peroxide mixed with baking soda and water or, dishwasher detergent (Cascade) and boiling water. I chose the "Cascade" method. This worked wonderfully; cleaned my coffee blackened, large thermos to a like new finish in 15 minutes with just two rounded tablespoons of detergent. Thank you David K., JMRoss, Susan from ThriftyFun, and others who suggested this method. Thank you also, Sandy, for letting me know bleach was a bad idea, that it would damage the seal/weld.

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April 21, 2009

Coffee stains in stainless steel thermos. How can they be removed?

Shirl from Medford, OR


Cleaning a Stainless Steel Thermos

Shirl, I think it's possible to mix up some warm baking soda and water and put inside the thermos and then let it set a while. If you have a long brush to use inside it, then you should be able to brush the stains right off. Just using the brush with sudsy hot water would probably work. It has for me in the past and I am always amazed at how clean and sparkly the inside of the thermos looks. I guess it just depends on how long the stains have been there as to how much work you have to do to remove. Hope this helps. (09/06/2006)


By Debbie Dzurilla

Cleaning a Stainless Steel Thermos

What works for me is a couple of tablespoons of dry dishwasher detergent, then fill the bottle with hot water. Leave a little room at the top and put on the cap. Shake every so often and let it sit overnight. It really works. Susan from ThriftyFun (09/06/2006)

By ThriftyFun

Cleaning a Stainless Steel Thermos

I would try filling the thermos with water and then dropping in a couple of denture cleaning tablets. Let sit for a couple of hours. Then rinse well or wash as normal. I've used them to clean small flower vases, etc. (09/08/2006)

By Harriet

Cleaning a Stainless Steel Thermos

I have cleaned my stainless steel thermos by having a small handful of gravel from my driveway. Rinse off your gravel stones, put them with water in your thermos & shake it around real well. Then empty them out & wash out normally. Hopefully this should help you out. I don't know about coffee stains, but it may help. (09/08/2006)


By Ace

Cleaning a Stainless Steel Thermos

I agree with Debbie 52. My husband worked Monday through Friday. Friday night, I would put sudsy hot water in his thermos and shake it vigorously. Then rinse it well. Add about 2 tablespoons of baking soda and fill with HOT water. Put the lid on and shake. In the morning, shake again and then rinse well. Clean as a whistle and ready for Monday morning coffee. Hugs. (09/08/2006)

By Penny Stoehr

Cleaning a Stainless Steel Thermos

Lemon Juice (fresh or bottled) or vinegar. First take about a cup of any one of these, swish it around the thermos without diluting it then mix in some water (about 1 part vinegar or lemon juice & about 3 or 4 parts of water) and soak at least a few hours or overnight, then rinse with warm water. This is how they recommend you clean out coffee pots, so if vinegar can clean coffee stains, I'm sure it will clean out your thermos.


One more option if none of these work. I've bought stainless steal thermos used at second hand stores before and to rid them of any germs, I've used a small amount of bleach (about 1 to 2 inches in the bottom) and added warm water. This worked great for me. Bleach works great on plastic and glass thermos too! (09/08/2006)

By Cyinda

Cleaning a Stainless Steel Thermos

At work we have stainless coffee pots. I clean them with very hot water and dishwasher detergent. While cleaning I forgot about them, when I went back and rinsed them out they were the cleanest they have ever been. (09/11/2006)

By Julie

Cleaning a Stainless Steel Thermos

I used to clean my stainless steel thermos with a retail product found at the grocery store called Dip-It. It worked great! A dry, granular product that you would mix with boiling water in the thermos. The mixture would bubble a little and in an hour or so all stains would be gone. My last package (8 oz?) lasted years and now I can't find it at the store. (02/24/2007)


By jughead

Cleaning a Stainless Steel Thermos

Someone mentioned using bleach to clean a stainless steel thermos. This is very bad advice. The chlorine in the bleach, if it comes in contact with the weld near the top of the thermos will destroy that weld, and your thermos bottle will no longer keep liquid hot or cold. I found this out the hard way, and was informed of the dangers of bleach on stainless steel thermos bottles when I spoke to someone at the Thermos company. (10/01/2007)

By Sandy

Cleaning a Stainless Steel Thermos

The first time at your site someone suggested a dishwasher cleaning tablet (we use Electrosol) in the pot with hot water. I tried it and in 15 minutes my pot was spotless, and it was pretty bad as I had not cleaned it for several months. Previously I used stainless steel cleaner and scrubbed forever with a brush. Whoever sent in that tip thank you, thank you. A spotless pot with no scrubbing. (12/25/2007)

Cleaning a Stainless Steel Thermos

I've got it; hydrogen peroxide and baking soda. I tried everything to remove completely black stained thermos travel mugs and big thermos. After buying a new one and seeing how shiny the steel was, I became determined to find the ultimate cleaner. After reviewing everything on this and other sites, I experimented with hydrogen peroxide. After half an hour, not much happened. I added baking soda, magic! Without scrubbing or anything, I just rinsed them out and they were cleaner than the new one (we did have a few cups of coffee in the new one - so it wasn't spotless). I used a ratio of 2 parts hydrogen peroxide and 1 part baking soda. But, you can experiment. I don't know what the optimal amount is. Don't even bother trying anything else. It works. Period. (02/13/2008)

By coffeegeek

Cleaning a Stainless Steel Thermos

The Electrosol method works beautifully. Just drop an Electrosol tablet (mine had the power ball) and fill SS Thermos most of the way with boiling water. Shake every few minutes. After fifteen minutes, pour out the water and residue. Rinse a few times with clean water. Your Thermos will be gleaming on the inside. Amazing. (04/26/2008)

By David K.

Cleaning a Stainless Steel Thermos

Wow, I had a stainless steel pot that looked so bad I thought it had rusted through, completely black, the coffee that came out of it tasted horrible. I grabbed some Cascade (dishwasher soap), poured about one dishwasher loads worth in, then poured in boiling water (not hot water, boiling). Then I put the lid back on, and gave it a good shake ever 5 minutes for about 15-20 minutes. Poured it out and the pot was nearly spotless. Repeated this once more and then dropped in a paper towel and used a fork to wipe it around, and the thing looks like it just come from the store. Coffee no longer tastes horrid any more, amazing, if someone told me to do that I would have laughed, I thought the pot was a goner. (06/19/2008)

By Joe

Cleaning a Stainless Steel Thermos

I tried the method listed above to clean a very stained stainless steel travel coffee mug. First, the bad news. I put in a small amount of Cascade, added boiling water, screwed the cap on and gently shook it. Well, the top seal of the mug blew out from the pressure spraying boiling water all over my hand. The good news is that despite the very short time the detergent was in there, the thing cleaned up like new with a little rinsing. So, be cautious with this method. (10/13/2008)

By Bob W

Cleaning a Stainless Steel Thermos

I had a stainless coffee pot that was about 2 years old and had lots of build up. I tried David K. post remarks and he is right on. Worked in 5-10 minutes. Thanks (12/04/2008)

By Douglas P

Cleaning a Stainless Steel coffee pot

As odd as it sounds, salt and ice cubes in stainless steel coffee pots with a very little amount of water works very well. Add these three ingredients and shake it around. Amazingly it pulls even the worst coffee stains off of the bottom of an otherwise burnt pot of coffee (12/04/2008)

By FF14Reed

Cleaning a Stainless Steel Thermos

I just wanted to second where someone said to use hydrogen peroxide and baking soda. I have two thermoses and one of them was really nasty. It was totally black and I tried lots of different ways to clean it. Nothing worked. I bought some of the big hydrogen peroxide bottles from Costco. I filled the offensive thermos with it and used about 1/3 to 1/2 a normal box of baking soda. I put the top on and shook it hard and then took the top off and let it sit over night.

The following morning I saw a layer of black substance floating on top of the liquid. I dumped the hydrogen peroxide/soda mix out and rinsed it out. It was totally clean inside. It looked new, no exaggeration. I even showed my wife and she too was amazed. This really works and it couldn't be easier. You won't be disappointed, I promise. (12/11/2008)

By Unklfungus

Cleaning a Stainless Steel Thermos

I just used the dish washing/boiling water method for about an hour and it worked great! The other methods are probably fine, but for me this was the most convenient. (12/28/2008)

By Roger D

Cleaning a Stainless Steel Thermos

Oh my gosh you are all awesome. I have a Starbucks thermos coffee pot, so coated, coffee tasted terrible so I was looking to Starbucks for a replacement thermos. After not finding one, I found you all. I used Palmolive Eco liquid dish washing detergent, hot water, in less than 5 min of stirring the mixture 95 percent was gone. I had to go to work, came home another 5 minutes same treatment, the pot is totally clean. Thank you so much. (01/13/2009)

By Tancee

This Method Works!! Cleaning a Stainless Steel Coffee Pot

Incredible! I just used the Cascade liquid dishwasher soap method discussed here. I put a little less than a dishwasher loads worth in our Kitchen Aid stainless steel 10 cup pot, shook it a little to spread it evenly along the bottom, put a pot of water on to boil (about 5-6 cups of water) and then poured the water into the coffee pot that was sitting with the Cascade in it.

I put the sealed lid on the pot (I was careful to shake the pot moderately in a level position to let the pressure in the pot escape out of the vented pouring top, given the experience of one of the writer's below on it exploding a bit when the pot was not shaken to let it vent) and after about a minute of shaking, let the pot sit for another 2-3 minutes on the counter.

I then came back, gave the pot another shaking for less than a minute and then poured out the contents. It was incredible - the pot looked brand new inside with every bit of built up coffee crud removed. Definitely saved the pot from the scrap heap and since you know Cascade is safe since you wash dishes with it, I'm happy to just rinse out the pot and get fresh coffee the way it's supposed to taste.

Thank you to whomever figured out this cleansing recipe. It is a real demonstration on the power of concentrated Cascade, but it definitely gets the job done fast and easy with no physical effort. (01/31/2009)

By N Cheng

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