# How can I clean the coffee stains from the bottom of my thermos?
**URL:** https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806
**Category:** Factual Questions
**Created:** [December 30, 2000, 5:51pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806 "2000-12-30T17:51:23Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Tiburon](https://boards.straightdope.com/u/Tiburon)
#### Post date: [December 30, 2000, 5:51pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/1 "2000-12-30T17:51:23Z")
Hey there, folks.
I’m a coffee drinker and I have a little stainless steel slimline thermos (from Starbucks - anyone seen these?). It works like a charm but the bottom of my thermos is pretty stained. If it doesn’t affect the taste of the coffee (is that a build up of coffee gunk?) then I really don’t care - but either way, is there a way to clean this up? I admit, like a bird, I like bright shiny things, even if it’s at the bottom of my thermos.
Tibs
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### Author:  [@scratch1300](https://boards.straightdope.com/u/scratch1300)
#### Post date: [December 30, 2000, 5:54pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/2 "2000-12-30T17:54:50Z")
What have you tried? A bottle brush?
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### Author:  [@3waygeek](https://boards.straightdope.com/u/3waygeek)
#### Post date: [December 30, 2000, 5:57pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/3 "2000-12-30T17:57:11Z")
One word: bleach.
Put a bit (a tablespoon or three) in the Thermos, fill it the rest of the way with water, and let it sit a while.
Make sure to thoroughly rinse before putting coffee in it 😉
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### Author:  [@Tiburon](https://boards.straightdope.com/u/Tiburon)
#### Post date: [December 30, 2000, 6:14pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/4 "2000-12-30T18:14:23Z")
What have I tried?
Not the bottle brush - couldn’t find one thin enough.
Uh…I did try shoving the wash cloth down there and moving it around with a salad spoon.
Anyone up for salad?
Tibs
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [December 30, 2000, 6:51pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/5 "2000-12-30T18:51:08Z")
> [@](#):
>
> \*Originally posted by Tiburon \*
> \*\*What have I tried?
>
> Not the bottle brush - couldn’t find one thin enough.
>
> Uh…I did try shoving the wash cloth down there and moving it around with a salad spoon.
>
> Anyone up for salad?
>
> Tibs \*\*
\
Do as 3waygeek directs. Bleach and a stiff bottle brush will clean it out.
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### Author:  [@DonJuanDeMarco3](https://boards.straightdope.com/u/DonJuanDeMarco3)
#### Post date: [December 30, 2000, 6:54pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/6 "2000-12-30T18:54:20Z")
There is a solvent cleaner called CLR in a grey hi-tech looking bottle in the cleaners section at a walmart type store. I would recomend it for cleaning out the coffee pot too. If you put it through, it makes the coffee alot better. Just follow the directions.
P.S. it doesn’t just get off **C** alcium **L** ime and **R** ust
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### Author:  [@Green\_Bean](https://boards.straightdope.com/u/Green_Bean)
#### Post date: [December 30, 2000, 7:08pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/7 "2000-12-30T19:08:40Z")
Or you could try denture cleaner. Just follow the package directions, but instead of putting your teeth in the solution, put the solution in the thermos. This method has the advantage that the denture cleaner is formulated to be used on something that goes in the mouth.
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### Author:  [@kinoons](https://boards.straightdope.com/u/kinoons)
#### Post date: [December 30, 2000, 7:53pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/8 "2000-12-30T19:53:57Z")
mouthwash. It worked great on my camelback in both getting any stains out and removing flavors that seaped into the plastic.
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### Author:  [@nineiron](https://boards.straightdope.com/u/nineiron)
#### Post date: [December 30, 2000, 8:54pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/9 "2000-12-30T20:54:58Z")
Nah. Leave it. Everyone knows that the old coffee residue makes the coffee taste better. 🙂
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### Author:  [@Nancyfish](https://boards.straightdope.com/u/Nancyfish)
#### Post date: [December 30, 2000, 9:10pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/10 "2000-12-30T21:10:13Z")
Throw in a handfull of small ice cubes, 1 tsp. salt, 1 tbl. lemon juice. Put the lid on and shake it around a while.
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### Author:  [@barbitu8](https://boards.straightdope.com/u/barbitu8)
#### Post date: [December 30, 2000, 9:40pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/11 "2000-12-30T21:40:17Z")
If you’re a real coffee drinker you wouldn’t be using a thermos. I like my coffee piping hot **AND FRESH**.😃
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### Author:  [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)
#### Post date: [December 30, 2000, 10:49pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/12 "2000-12-30T22:49:46Z")
> [@](#):
>
> \*Originally posted by Squidwife \*
> \*\*Throw in a handfull of small ice cubes, 1 tsp. salt, 1 tbl. lemon juice. Put the lid on and shake it around a while. \*\*
I second this one, it works great!
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### Author:  [@mangeorge](https://boards.straightdope.com/u/mangeorge)
#### Post date: [December 30, 2000, 11:06pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/13 "2000-12-30T23:06:57Z")
Baking soda works good. Make a paste in the thermos and let it sit awhile. Then brush. You do need a brush.
And don’t listen to **barbitu8**. Your coffee will taste fine, as long as you don’t re-heat it or keep it too long. And keep your thermos clean, which is what you’re trying to do.
BTW; Starbucks is now supermarket coffee. Does that ruin it for anybody?
Peace,
mangeorge
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### Author:  [@barbitu8](https://boards.straightdope.com/u/barbitu8)
#### Post date: [December 30, 2000, 11:31pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/14 "2000-12-30T23:31:26Z")
Doesn’t ruin it for me. I don’t like it anyway.
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### Author:  [@handy](https://boards.straightdope.com/u/handy)
#### Post date: [December 30, 2000, 11:54pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/15 "2000-12-30T23:54:40Z")
Try some rice, uncooked & Put in some water & a little soap.
One cleans fancy flower glass vases this way 🙂
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### Author:  [@FormerlyKnownAsBlank](https://boards.straightdope.com/u/FormerlyKnownAsBlank)
#### Post date: [December 31, 2000, 5:17am UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/16 "2000-12-31T05:17:30Z")
There’s a great product **Zud** cleanser, on the store shelf next to Comet. It has special stuff to remove rust, which is basicly what the stain is.
You can also use something called CLR (Calcium/Lime/Rust) cleaner, which is a liquid. In most supermarkets and all Walmart or Ace hardware stores.
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### Author:  [@Frannie](https://boards.straightdope.com/u/Frannie)
#### Post date: [December 31, 2000, 6:27am UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/17 "2000-12-31T06:27:02Z")
liquid dishwasher detergent
soak for a bit
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### Author:  [@Frannie](https://boards.straightdope.com/u/Frannie)
#### Post date: [December 31, 2000, 6:28am UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/18 "2000-12-31T06:28:15Z")
(I know… technically, that’s bleach.)
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### Author:  [@mangeorge](https://boards.straightdope.com/u/mangeorge)
#### Post date: [December 31, 2000, 6:50am UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/19 "2000-12-31T06:50:43Z")
Been searchin’ around. Here’s what I found at
[http://www.tipking.com/Houshold/hold0033.htm](http://www.tipking.com/Houshold/hold0033.htm)
> [@](#):
>
> A fizzy way to clean a thermos
> Fill the bottle with water, drop in four Alka-Seltzer tablets, and let soak for an hour (or longer, if necessary)
If you try this, let us know how it works.
BTW; The Thermos site specifically said **not** to use bleach.
Peace,
mangeorge (Time on my hands)
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### Author:  [@Persephone](https://boards.straightdope.com/u/Persephone)
#### Post date: [December 31, 2000, 2:50pm UTC](https://boards.straightdope.com/t/how-can-i-clean-the-coffee-stains-from-the-bottom-of-my-thermos/47806/20 "2000-12-31T14:50:32Z")
I’ll third the salt & ice method. I used to work at Dunkin’ Donuts, and this is the method we used, but without the lemon.
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