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
What have you tried? A bottle brush?
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 
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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Do as 3waygeek directs. Bleach and a stiff bottle brush will clean it out.
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 Calcium Lime and Rust
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.
mouthwash. It worked great on my camelback in both getting any stains out and removing flavors that seaped into the plastic.
Nah. Leave it. Everyone knows that the old coffee residue makes the coffee taste better. 
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.
If you’re a real coffee drinker you wouldn’t be using a thermos. I like my coffee piping hot AND FRESH.
I second this one, it works great!
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
Doesn’t ruin it for me. I don’t like it anyway.
Try some rice, uncooked & Put in some water & a little soap.
One cleans fancy flower glass vases this way
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.
liquid dishwasher detergent
soak for a bit
(I know… technically, that’s bleach.)
Been searchin’ around. Here’s what I found at
http://www.tipking.com/Houshold/hold0033.htm
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)
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.