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How to Remove Coffee Stains From a Stainless Steel Carafe

The inside of your thermal carafe has gone brown and smells stale, and scrubbing hasn't fixed it. Brewers have a soak for that.

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Digby wrinkles his nose as he tilts a steel thermal carafe toward himself, its inside streaked dull brown, a damp sponge and a small box of baking soda on the counter.

Someone in r/Coffee had a carafe that had picked up a flavour and smell of its own. Soap, baking soda and vinegar weren't clearing it. Half a teaspoon of an espresso machine cleaner and an hour in hot water, and the water came out chunky. Their verdict on the inside of that carafe: it wasn't stained, it was coated.

That cleaner is a powder, and it has relatives. Homebrewers keep a tub of one for their brewing kit and use it on coffee carafes too. The laundry aisle sells a third.

If your thermal carafe is brown inside or smells stale however you wash it, this is the soak brewers and coffee people reach for.

The brewers' soak

The three powders share one working part, sodium percarbonate. Dissolve it in hot water and it splits into sodium carbonate, which is an alkali, and peroxide. A brewery cleaner like PBW is built on that pair.

I've got a stainless carafe that has a lot of miles on it and I'm not that great at cleaning it. Let 160F water and PBW soak in it and it's as good as new. All of the brown stains are completely gone.

The brewer who started the thread, in r/Homebrewing

Two replies back it up. PBW does wonders on coffee stains in a stainless carafe, one reply says. Another brewer runs it through the coffee maker and the carafe both.

An older thread among the same brewers has it stripping coffee stains off stainless and cleaning stainless cookware while it's at it.

How to deep clean a stainless steel coffee carafe

The powder does the work. Your part is heat, time and rinsing.

  • Hot water. Fill the carafe. The brewer above used water at 160°F, hot but not boiling.
  • A small spoonful. Half a teaspoon of Cafiza was enough for the coffee poster's carafe.
  • An hour, or overnight. One hour was enough for the coffee poster. A brewer who soaks a stainless coffee cup overnight says it looks amazing after.
  • Rinse, then rinse again. The coffee poster's own warning, because their first pot afterwards tasted a bit soapy. The Cafiza safety sheet says swallowing it can bring on nausea and an upset stomach.
Close up from the side, Digby pours steaming water from a kettle into the upright carafe, fine bubbles fizzing at the rim, a white tub at the edge of the frame.

OxiClean Free, PBW or Cafiza?

Same soak, three tubs. PBW is sold to brewers, Cafiza to baristas for espresso machines, and OxiClean Free sits in the laundry aisle.

Brewers in both threads say the laundry tub does the job for less. One brewer's version: PBW is great, but there are cheaper options. The overnight brewer had stopped buying the real thing and uses OxiClean Free instead.

Over in the coffee thread, the reply to "Cafiza is no joke" was that OxiClean Free has the same active ingredient. The safety data sheets back that up and stop it going further.

All three list sodium percarbonate. PBW and OxiClean Free are mostly sodium carbonate, which is washing soda, with the percarbonate second. Then each maker adds its own helpers: PBW a chelator, Cafiza a surfactant and a pyrophosphate, OxiClean Free a surfactant or two.

Same active ingredient, different recipe. The overnight brewer even adds trisodium phosphate to the OxiClean Free, having heard it gets closer to PBW.

The only dissent is a commenter in the coffee thread who won't put OxiClean in a food vessel at all, and uses plain trisodium phosphate instead. Replies elsewhere in that thread point at the fragrance in regular OxiClean, which the Free version is sold without. Free is the one the brewers and the coffee replies name.

What to keep it away from

  • Aluminium. The brewer who runs PBW through the coffee maker is emphatic that it doesn't go on aluminium. The same active ingredient is in all three, so treat that warning as covering the lot. Everything soaked in these threads was stainless.
  • Rubber and silicone. The commenter who won't use OxiClean also warns that Cafiza can denature the rubber in gaskets and seals. Nobody else raised it. What one owner did find is that an OxiClean soak took the stains out of a travel mug and not the smell in the gasket. The soak is for the steel, so don't count on it for the lid.
Digby tilts the carafe toward himself with a small proud smile, the inside now clean bright silver, a steaming mug of coffee on the counter where the sponge was.

Start with whichever tub is nearest. A spoonful of OxiClean Free from the laundry cupboard and an overnight soak is tonight's answer. Cafiza or PBW is the order to place when you'd rather have the powder made for the job. Whichever you pick, rinse it well, and the next pot will taste of coffee instead of cleaner.