Stainless steel pot discoloration?

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Dazed & Confused
KKF Supporting Member
Dec 31, 2020
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I have a couple Calphalon stainless pots that have developed some colorful discoloration. Looks like tempering colors? Is this anything to be concerned about?

Yep nothing to worry about. I get some rainbowing in all my stainless. It seems more prevalent in my pots and I've just chalked that up to how hard our water is.

Also, something that doesn't get enough mention is to not add salt your water until it's close or at a boil. You want it to dissolve quickly as it can attack the stainless.
I've seen this depending on what I'm cooking - seem like minerals etc can cause this. Nothing to worry about in pots that I've had for decades. You can use stainless steel cleaner to remove it if you'd like

Hmmm, now that you mention it, these same two pots used to get white residue at the bottom that I could clean off with BKF. I stopped bothering at some point so maybe that white residue has turned into this multi colored rainbow.
BKF removes this for me. You can also try white vinegar and some time.
what I see in the picture looks a lot like what I saw in our previous pots when I f.e. took a pot full of boiling pasta plus water off the heat and drained it to then put the pot back on the heater(turned low or off). Our current pots (Fissler Pro) have far thicker bottoms that somehow provide much more even heat and tend not to overheat. Did I already say I LOVE these pots?
It's possible that the grade of steel makes a difference in how easily it occurs... 18/0 vs 18/8 vs 18/10.
My French made Cuisinart pans have the same patination. I've noticed its more pronounced on my induction stove compared to the old Schott Ceran halogen.
that certainly! Stainless can not deal with salt really well unless you use the more fancy alloys.

(Safest &) Best Stainless Steel Cookware - 2021 Guide
I think even fancy alloys have a lot of problems with salt + acid. There are tables that discuss the corrosion rate in acidic salt water and its pretty high. Anecdotally, I used to soak my SS pans in vinegar after cooking to make cleaning easier. Don't do that 😭
I get this on my stainless pots and pans, too. It comes and goes, depending on what I've cooked. Nothing to worry about, unless you hate the visuals of this. Personally, I don't care :)
Once cleaned with dishwasher soap, drop a teaspoon of white vinegar. Spread it with paper towel or fine steel wool. Then rinse and dry and there should be no trace at all.