How should I clean a stainless coffee carafe?

Question

At the office, we have a coffee maker with a stainless steel vacuum carafe similar to this one. It has accumulated coffee residue in it from 5+ years of hard service, whilst receiving in return what I shall politely call "inadequate cleansing."

It's a double-wall vacuum container. There is no heating element, so I'm not exactly sure what causes this buildup in the first place. The manufacturer user manual suggests to clean using dish soap / mild detergent, or the top rack of a dishwasher; I've tried both, neither worked. I have also tried scrubbing with non-abrasive brush, sponge, and dish detergents; improved, still lots of residue. I soaked in two batches of near-boiling water and bicarb (baking soda) for about an hour. The first rinse looked almost like brewed coffee; this was shocking. After all that, the situation was improved but there's still lots of residue.

There are myriad suggestions for removing coffee stains from stainless steel, like this set of eight (8) from Wikihow. It suggests exposing the inside to various household chemicals: vinegar, baking soda / bicarb, bleach (!?), salt, ice cubes, etc. This other article suggests using a dishwasher detergent tablet but it uses anonymous tablets. It does give a nod to using dishwasher detergent powder (as I did with this other device), but I'd prefer to know what is the actual cleansing chemical at work.

So before I either abandon this (decidedly serviceable) carafe for a new one, or begin indexing my pantry for candidate chemicals: How should I clean this stainless carafe? Surely someone must have had and solved this problem.

In addition: I'd also like to ensure that I don't make this worse in the process; e.g., scratching or etching the inside of the carafe. Are these carafes predisposed to buildup? What's causing it? Besides regular cleaning, is there anything else that will keep this thing cleaner for a longer period of time?

Answer 1

Tannin is a chemical contained in coffee and this is what normally stains your coffee making / drinking equipment.

When using an espresso machine it is advised to 'backflush' your machine with cleaning powder which cleans away a build up of 'tannin' from inside the machine. I expect a similar thing has happened to your carafe. With an espresso machine you're advised to do it weekly with heavy use - so I can imagine an "inadequate cleansed" carafe would probably be heavily tannin stained.

You can purchase tannin cleaning powder from any coffee supplier, such as Happy Donkey.

Even though it is designed for Espresso Machines - it is perfectly safe to dissolve the powder in water and use it to clean other tannin stained equipment.

Answer 2

I have a Bunn coffee brewer with a stainless steel thermal carafe. I have cleaned it, following the instructions in the owner’s manual and the results were surprisingly good.

Place a paper filter in the brew funnel and pour 2 teaspoons of Cascade powder dishwashing detergent into the paper filter. Pour one carafe of cold water into the brewer and brew. Allow carafe to sit for 10-15 minutes. Using a long handled, soft bristled brush, clean the inside of the carafe. Pour out the solution and rinse thoroughly.

The owner’s manual mentions “Cascade” by name. The ingredients in Cascade follow.

Water softeners (complex sodium phosphates and sodium carbonate), cleaning and water spot prevention agents (non-ionic surfactant and chlorine bleach), dishwasher and china protection agents (sodium silicate), processing aid (sodium sulfate), suds control agent and perfume.

I don’t know of any way to prevent the buildup other than regular cleaning.

I hope this helps!

Answer 3

Imposing as the build-up of dark staining on the wall of your stainless steel carafe may seem, I predict it will come up with water and a bit of effort with a paper towel or other light cleaning tool. I recommend using cold or lukewarm water as this will allow you rub at the (layers of) stain without risk of pain from hot water.

The build-up is largely from water soluble compounds in the coffee, and because the brewing process creates a concentration of these in hot water, as the brew cools these tend to come out of solution. There will also be tiny particles of ground coffee, small enough to make their way through the filter/basket that holds the original coffee grounds, and these particles act to promote the staining/sedimentation, esp. at the bottom of your carafe.

You've already seen the first evidence of success when the rinse water came out almost as dark as the brewed coffee the carafe normally holds. It's large a matter of repetition. However if the carafe were used to hold some coffee mixed with something else, such as milk or creamer, this can make a more difficult cleaning problem (because the fat in milk will act as a binding agent that resists water solution). I assume that is not the case here since most people in the office will have their own preferences for adding milk or other creamers, if any.

It's a bit easier to see how quickly the staining rinses out of a glass carafe (several rinses may be needed, judging by your description of the build-up), but there's nothing about a steel carafe that would make the staining more difficult to remove.

Answer 4

I too used mild soaps, detergents, bleach, vinegar and scrubbing in a double walled 16 oz. stainless coffee cup, yet the coffee stain remained. I finally used Cascade powdered dishwasher soap with great success, ending with uncolored stainless and no etching. I put approx. 1/4-1/2 teaspoon in the cup, fill with hot water, shake mixture and set it overnight with lid on. I recently used a small amount from a Cascade POD of powdered dishwasher soap with the same success. The Cascade dishwasher liquid detergent does NOT work. Good luck!

Answer 5

I brew a pot with ~10% vinegar and it cleans everything right up. A second run of just water is done to help with any residual vinegar.

Answer 6

I have finally found the quick & EASY way to clean my stainless steel coffee carafe. I am just amazed! It worked like magic. Just put a Cascade dishwasher detergent pod inside of your carafe. Boil water on the stove and then put your carafe in the sink and fill it to the top with the boiling water. It only takes about 30 minutes. I did this, walked my dogs, came back and by the time I got back the water in the pot was black. I used a long-handled spoon to stir it (know anyone who can fit their hands in one of these?!), poured the BLACK water out and it was spotless. I don't mean pretty clean. I don't mean very clean. I mean SPOTLESS. I don't think my stirring with the spoon made one little difference. I think Cascade and boiling water did that all on it's own. So happy!

Answer 7

There’s a food safe degreaser called KrudKutter. Its the oil that sticks and stays. I’ve used it for glass carafes also. Spray, wipe and done. If it’s a tough buildup, do a few times. Works every time!

Answer 8

Failing other methods, use Barkeeper's Friend, a commercial general purpose cleaning product you can find in most supermarkets. It's a powder that you sprinkle on whatever needs to be cleaned, then add a small amount of water and scrub. This stuff works miracles on stainless steel and is the go to cleaner at many restaurants and bars.

Buildup there can be caused by the evaporation of water, leaving behind solutes in a layer known as "scaling". Or it could be something else, hard to tell without seeing it and learning your process. Barkeeper's Friend can get rid of most possibilities and is a useful cleaning product to have on hand for other purposes.

Answer 9

I have found a longer soak (overnight, usually) after preheating cold container with boiling water - wait for container to warm, dump water and refill with fresh boiling water and bicarb/baking soda generally solves my stainless steel thermos, which is functionally similar, and sometimes gets more interesting gunk (as I tended to put milk and sugar in it, so if it was forgotten for a while after use, it really needed cleaning...)

Answer 10

Others will disagree, and perhaps rightfully so, but I pour just enough bleach to cover the bottom. Wait 1 minute and then slowly and carefully hold the carafe sideways and slowly twirl the carafe so that bleach eventually touches all if the inside. Then carefully fill with water and pour it out. Rinse, rinse, rinse! I often see not to use bleach on SS, but I’ve had no trouble.