Does Putting Aluminum Foil in Your Dishwasher Really Remove Water Stains? I Asked a Chemist
For as long as I can remember, my mom has always dropped a crumpled ball of aluminum in the dishwasher. She would place it right next to the utensils, pop in a tablet, and turn on the machine like what she did wasn’t sufficiently mysterious. I always thought it was a way to give old aluminum foil a second life — kind of how we let paper towels dry for a second use or dunk a tea bag into one more cup before tossing it. But then I saw the kitchen staff do the same thing when I was a waiter in college, confirming this was some kind of magic cleaning trick.
According to my mom, who is a professional housekeeper whose tricks of the trade have always served me well, the aluminum foil helps reduce the appearance of water stains and makes the glass sparkle a little more. (This is especially handy if you sometimes get cloudy drinking glasses.) While I never questioned her methodology and continued using aluminum balls when I moved out, I did begin to wonder if this actually works. And if it does, what is the science behind it?
Does Using Aluminum Balls Actually Work?
Spoiler alert: As it turns out, it only kind-of-sort-of works, and only for utensils, not glassware. “Aluminum in the dishwasher will make absolutely no difference to ceramic or glass dishes,” said Dr. Kat Day of The Chronicle Flask, who is a science writer with a PhD in chemistry. “There’s no plausible mechanism for this, other than perhaps foil balls bouncing around and mechanically knocking things off the surface of plates or bowls, but that’s not going to be very effective. It’ll probably impede the dishwasher, if anything.”
Sorry, mom. As for the utensils, it might help clean them, but only if the aluminum is very close to them. “I suspect this has come from the idea that you can clean silver (specifically) with aluminum foil and salt solution,” Day shared. “However, to do this, the silver object (cutlery, in this case) needs to be in direct contact with the foil.” It wouldn’t work if the foil was on the other side of the dishwasher or bouncing around the bottom of the appliance.
Reversing the Tarnishing Process
Placing tarnished silver in direct contact with aluminum, baking soda and hot water is said to help reverse the tarnishing process due to an electrolytic reaction which transfers the oxidized tarnish from the silver to the aluminum foil. That’s because the baking soda pushes electrons to move back and forth between the silver and aluminum. “Since aluminum has a much higher affinity for sulfur atoms than silver, the silver ion is reduced back to silver, and sulfide ions are released,” wrote myth-busting publication Bellatory in an article explaining the science behind cleaning tarnished jewelry. “These bind to aluminum to form aluminum sulfide. The aluminum corrodes, and the silver turns shiny.”
This could happen with your utensils since the detergent pod acts as the salt bath needed in this reaction, and the aluminum foil is in contact with the silverware. However, as Day mentioned, this is only the case if the aluminum firmly stays near the cutlery. But since you’re just recycling gently used aluminum sheets, I still say it’s worth trying!