I have a stainless steel coffee mug that Irene bought me a while back that I really like. I use it several times a day. It is an extremely well made Oxo mug [1], highly polished inside, so it took a long time to build up a stain. But eventually, even a really good coffee mug needs more than just plain soap and water to make it sparkle.
So, I did a bit of research: how do you clean coffee stains from stainless steel coffee mugs [2]? The two suggestions I found that sounded easiest were baking soda or powdered dishwasher detergent. In either case, you mix a tablespoon or so of powder with a full cup of water, shake or stir, and let it sit for a while. Sounds easy enough.
I couldn’t find any baking soda, and Irene was already asleep for the night. So dishwasher detergent it is. We have those little tablets instead of granules, but I’m a handy guy: take the tablet still sealed in plastic, pound on the counter top- voila, powder. I wasn’t sure exactly how much to use, but the entire tablet had been powdered, so I poured the whole thing in. I added water from our “instant boiling water” dispenser, closed the cup, shook, and set it on the counter. I then wandered back to my computer to continue my usual wanderings around the Internet.
A few minutes later, there was a BANG! and some rattling sounds from the direction of the kitchen. I knew the kitten had been playing around a bit, so I went to see what kind of trouble she’d gotten into. What I saw when I arrived took a few minutes to process.
On the floor was a strange black object. On the counter was an odd looking stainless steel thing, and lots of water lying about. After about 5 seconds I figured out what had happened: my coffee mug had exploded.
To be more precise, the dishwasher detergent had produced a lot of gas, and the sealed coffee mug was so air-tight (the Oxo mug is extremely well sealed) that it had no where to go. It blew the top (plastic) part of the mug cleanly off. I picked up the odd looking black bit, and realized it was the lid plus the ring that attaches the lid to the stainless steel. I noticed it was designed to snap back into place, so snap it back in I did. A few moments later, I found a rubber seal ring several feet away that was probably supposed to go on the mug before the plastic part snapped back on- unfortunately, it took a lot of force to put back together…and it’s a lot easier to apply compression force than expansion force with my bare hands.
I calmly shook the (slightly reduced) dishwasher detergent + water mixture in the mug again, cleaned up the mess, left the mug unsealed this time, then went back to the computer.
The end of the story is that the mug is beautifully clean- the dishwasher detergent removed the coffee staining without any scrubbing whatsoever, and did so in under an hour. I have a spare rubber seal in case I ever somehow get the mug apart again. Interestingly, the mug still seems to be totally water-tight, but I’m sure that rubber seal had *some* purpose.
And yes, I’m letting the mug soak in plain water to clean out any residual dishwashing chemicals. I knew the stuff was nasty, but the explosive power of the expanding gasses produced by simple dishwasher detergent is pretty impressive.