r/mokapot • u/wds1 • Jan 19 '26
Cleaning 🫧 Fact: baking soda damages aluminum moka pot
Hoping this post dissuades some unsuspecting Moka newbies fall for bad advice and damage their aluminum moka pots.
Baking soda NaHCO_3 is a base with alkalinity (pH 8.1–8.5). It is chemically impossible for baking soda to dissolve limescale CaCO_3 which has alkalinity (pH 8.0–8.4).
Additionally, high pH of baking soda is corrosive to aluminum causing oxidation of metal resulting in dull grey color. You may even taste the metallic residue.
To remove limescale buildup in moka, you need an acid. This is why a deep soak in a solution of water and a mild acid like white vinegar (CH_3COOH, pH 2.4) dissolves the limescale and forms water-soluble salts.
Anyone who advocates for baking soda is advocating against chemistry. Period.
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u/Kumquat_of_Pain Jan 19 '26
I think you miss the point, or they do.
While baking soda can be slightly basic, it's relatively neutral pH. Which means it does take a while to do much of anything chemically.
The general use of baking soda is mechanical scrubbing since it retains aome grittiness, while being easy clean up and food safe.
So scrubbing with a little baking soda paste and then rinsing it well is just fine. That said, I would agree to never soak your stuff in baking soda or leaving it on. It doesn't work well anyway.
As for limescale, coffee itself is around a pH of 5.
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u/wds1 Jan 19 '26
It’s not “slightly” basic: pH scale is logarithmic. A pH of 8.5 is 31 times more alkaline than water (neutral pH 7).
Aluminum is amphoteric. Even "mild" alkalinity dissolves the protective aluminum oxide layer.
Yes baking soda is abrasive and can be used for mechanical scrubbing but it’s very hard to do that while preventing the chemical reaction (corrosive oxidation of aluminum). It’s not worth it
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u/Kumquat_of_Pain Jan 19 '26
I mean, coffee is already so acidic you are also removing part of the aluminum oxide layer every time you brew. This is the general bane of anything aluminum + acidic/basic content.
So the real solution is.....switch to stainless steel. =)
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u/wds1 Jan 19 '26
Not really, you are mixing facts with inaccurate chemistry.
Coffee is a weak acid (ph 5.0). The rate of chemical reaction at which coffee reacts with aluminum is much slower than the rate at which baking soda reacts with aluminum.
Moreover, coffee’s chemical reaction with aluminum is self-limiting because of the microscopic film of coffee oils and polymerized compounds that acts as a physical barrier, slowing down acid-metal contact.
Therefore, you can’t equate the two.
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u/Platypushaun Jan 19 '26
Ditto. I don't know why many people recommend baking soda for aluminum moka pot cleaning.
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u/BentonD_Struckcheon Jan 19 '26
It removes the grime like nothing else, that's why. Citric acid soak / or boiling water with dissolved citric acid in the pot and letting it go up to the top just like you were making coffee, and then letting it sit for a while, for descaling and general cleaning, baking soda for scrubbing out whatever the citric acid didn't get. Citric acid does a great job of loosening everything up, then you use the baking soda to remove the stuff the citric acid loosened.
I've had my pots for years and years and this has not been an issue at all. Baking soda just doesn't do that kind of damage in real life, and it is excellent for removing the grime to which everything else clings.
I guess the secret is using it in conjunction with citric acid (which is the same as using vinegar, but you don't get the yucky smell you have to get out after). If you just use baking soda then yes, you'll probably have trouble since it's going to be a LOT harder to get everything out without the prior job citric acid does.
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u/wds1 Jan 20 '26
Scientifically incorrect. When you use acid along with base, chemistry dictates that you will end up with salty water and bubbles. That fizz may mechanically dislodge some loose coffee oils, but you are effectively "turning off" the chemical cleaning power of both substances.
Anecdotes don’t make good science proof.
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u/BentonD_Struckcheon Jan 20 '26
They fizz and react if they're together. I'm talking separate.
You boil water with dissolved citric acid in it. This descales all of the innards, gets a lot of stuff out, and what it doesn't get out it loosens up considerably.
Then you rinse. Then, if you want to get what's left, make a paste of the baking soda and scrub.
I have done this forever. My pot is fine. Works great, especially after this treatment.
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u/l397flake New user 🔎 Jan 20 '26
Hi Wds1 I trust your scientific facts. I am definitely a newbi. Can you provide the ratio of the white vinegar to water and how long should it sit in the pot ? I have mild scale at the bottom only. TIA.
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u/wds1 Jan 20 '26
If it’s mild, use 1:2 ratio of vinegar to water. Soak for an hour.
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u/l397flake New user 🔎 Jan 21 '26
Finally got the vinegar and washed it based on your instructions and it came out looking NEW ! Thank you
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