How Come My Brand New Stainless Steel Sink Stains?

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I'd have to agree with Mike..... "Submersion in water will not cause a breakdown of the protective chromium oxide layer."
decent SS submerged in swimming pool water doesn't rust ...well at least for 30+ years in my "test pool"
to get SS to rust one typically has to disrupt the chromium oxide layer, with mechanical abrasion being a great method.
cheers Bob
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On Tue, 23 Feb 2010 15:55:13 -0800 (PST), mike

Submersal in water will allow corrosion if anything breaches the protective oxide layer. Out in the air, the oxide layer could reapir itself. Not so if submergered.
see also: crevice corrosion
This is all VERY basic stuff, and not a secret.
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snipped-for-privacy@dog.com wrote in

It is?
Then why is it used for 1) that sink in your kitchen, which spends much of its time wet? 2) commercial food-service applications? 3) swimming pool equipment? 4) fasteners (screws, etc) which face extremely corrosive environments involving water? 5) automobile exhausts?
I think you're not quite understanding the reason why stainless steel exists in the first place...
--
Tegger


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wrote:

Your list doesn't address what I said.
see also: crevice corrosion
Crevice corrosion is the achilles heel of stainless. I have seen one inch diameter bolts made of 316 stainless corrode completely in half rather quickly due to being deprived of oxygen because of being submerged in salt water. You could lay the same bolt in a pile of damp salt and it would be fine.
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Tegger wrote:

sink in the kitchen and we have tap water with a high calcium content. Lots of calcium overlaying every water exposed surface in the kitchen and baths. I use LemiShine, a citric acid formula to cut the stuff. Fill sink with water with about a half cup of the LemiShine in it and let it sit for awhile. Also use that solution in the coffee maker and in the dishwasher, about 1/4 cup in there. Cuts all the calcium deposits with regular use. I just ordered a five-gallon bucket of the stuff online. I don't own stock in the company but wish I did.
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I hadn't thought of mineral deposits. Perhaps the OP's new sink has a surface texture that's more receptive to mineral deposits than his old sink.
I wonder if something like CLR might also work? CLR does a bang-up job of dissolving mineral deposits in our shower head.
--
Tegger


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"Stainless steel" as it is commonly referred to is really technically "corrosion resistant steel".
The corrosion resistance comes from the alloys' ability to form a protective layer of chromium oxide, though relatively thin and subject to damage.
My parents SS pool ladder lasted for YEARS (like 30+) without any rust...except in the region just above and below the water surface. It rusted in the "wave zone".
note: Not all SS's are non-magnetic. Even so called "good" 300 series stainless steels CAN be magnetic due to alloy & working (cold working or heavy polishing). So the magnet test can give erroneous results.
cheers Bob
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So if the chromium oxide layer gets damaged, then iron oxide can form?
What I don't understand is why a damaged chromium oxide layer wouldn't immediately re-form, since oxygen is abundant in the OP's environment.
Our 20-year-old kitchen sink has on occasion been scrubbed with a scouring pad, which must have the effect of breaching any chromium oxide layer; the sink has no rust of any kind.

Our kitchen sink is SS, and is magnetic.
--
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wrote:

Yes.
It does form almost immediately but it takes more than a monolayer of chromium oxide to give significant protection. Formation of a layer of reasonable thickness takes some time.

Mmmmm... probably scratched through the oxide layer in some places but I doubt that the scrubbing removed it. Chromium oxide Cr2O3 is pretty hard, not quite as hard as sapphire but close.
I've had the fun(?) of machining stainless steel, then using it with stump remover and having my beautifully machined and polished parts rust quite nicely.... :-( -- Best -- Terry
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assertion is surely nonsensical.
He contends that the OP's sink has discolored on account of oxygen starvation, but there is no evidence that the OP's sink's Cr2O3 layer was ever compromised.
I have a feeling that there are none in this group who have any real understanding of what is going on with the OP's sink, and are simply making up fantastic and impressive-sounding bedtime stories. <http://www.unc.edu/depts/jomc/academics/dri/idog.html
--
Tegger


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wrote:

There's nothing much to know. Stainless steel doesn't mean stain proof, it means stain resistant. Stainless steel like all steel is an alloy... there are literally hundreds of different alloys/grades of stainless steel. The types of stainless steel used for kitchenware are the lowest grades because home kitchen work does not entail the highly corrosive materials found in manufacturing, ocean vessels, chemical plants, etc. The typical kitchen sink is made of about the poorest grade stainless steel, it will stain and pit from exposure to strong acids, bases, and other common household chemicals... full strength vinegar/citrus allowed to sit will stain, as will ordinary table salt, full strength laundry bleach will stain/pit as will auto dishwasher detergent. Folks place all manner of common household chemicals into their kitchen sink, like soaking paint brushes (water based paints are a strong alkali), and then wonder why they notice stains. Using stainless steel pots for heating brines and acid pickling liquids will stain... for those items use porcelainized cookware... stainless steel cookware is considered nonreactive but not with everything and not for lengthy periods and/or high temperatures. The typical stainless steel cookpot is a slightly higher grade than used for household sinks. The typical stainless steel sinks from the big box hardwares are of the very pooest grade stainless steel... a very long way off from marine grades.
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On Tue, 23 Feb 2010 08:39:30 -0800 (PST), mg

Stainless looks nice but isn't really stainless. I had the same problem until I found a ceramic container to put our soap pump bottle in.
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On Feb 23, 10:20am, Jeff The Drunk wrote:

Well that makes me feel better knowing I'm not the only one who has had the problem (although I'm not sure why). In my case I have an extra hole in the sink for an under-the-sink soap bottle. So, I've now installed one of those.
I also have had another problem, though. I'm a bachelor and I sometimes fill a dirty glass with dish soap and water and set it on the rim of the sink to soak awhile. Low and behold, I now have a stain the shape of the bottom of a glass on the sink also. Oh well, I'm glad I learned before I really made some bad stains.
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On Tue, 23 Feb 2010 10:18:44 -0800 (PST), mg

My sink is 20+ years old. Still looks good after a Brillo pad, some Comet cleanser and elbow grease. Guess the years of wear now hide any marks in the sink. You might try some Comet and a Brillo pad in the sink and see if that helps remove marks.
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As another poster said, stainless can stain, but shouldn't rust.
*However*, I would be calling Kohler and tell them your "stainless" steel sink is staining. They are a reputable company that values their name and may not want to split hairs over the word "stainless". They may offer you something (replacement, etc...)
The worst they can say is "no".
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Maybe it shouldnt stain, is a bad batch of steeel possible, yes call kohler, they know whats up
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Joe wrote:

a stainless sink. Owner's manual? Can't recall. As for rust, stainless will rust, especially in salt air. It will also get rust stains from bits of steel wool left on the rim.
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Maybe it has a different surface finish than what you're used to. Brushed, maybe? I love stainless steel, but you have to know how to clean it.
Try different cleaning methods. Start with a paste of baking soda and dishwashing liquid to scrub the whole sink with a brush. It works wonderfully for me.
If that doesn't work, move up to using some acid cleaning, like letting vinegar soak on it or by scrubbing it with Bar Keeper's Friend (oxalic acid cleanser).
By the way stainless steel CAN rust slightly if it is a poor grade alloy with insufficient chromium. I doubt that is the case here.
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Wow! The baking soda/dishwashing liquid paste does work. I repeated the process 3 times (not scrubbing very hard), first cleaning it then rinsing and then drying and that eliminated about 80% of the stain with no scratches or marks, etc., from the cleaning process. Then I decided to try "Cerama Bryte" on the 4th go around. That's the stuff I use for my new smooth-top stove. That totally eliminated the rest of the stain.
Thanks Mike I really appreciate it. I'm trying not to turn into a fussy, old widower, but I want to all the trouble of replacing the water-damaged bottom of the cabinet and all of the trouble of installing the sink with a new disposal, along with new shut off valves, new supply lines and new drain pipe and then having the damn thing stain right off the bat was kind of a downer.
I'm guessing you're probably right about the finish, but I never really noticed the old sink. So, I'm not sure.
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After looking up "stainless steel magic", it looks like your cleaner is the problem. It is based on petroleum distilates which are fine for breaking down grease, but are useless for dealing with calcium deposits, which is likely what you have from water gathering under the bottle and evaporating.
You'll need an acid-based cleanser, as I mentioned in an earlier reply (vinegar, oxalic acid, etc.).
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