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Comment by klodolph | Hacker News Reader

Stainless steel does rust and does stain. It is much more resistant to rust or staining than ordinary carbon steel.

Think of it as “stain-resistant” and “rust-resistant”.

Except my sink has not rusted or stained in 20 years I've had it. Surely they could use a particular grade of SS to mitigate?

How often do you clean your sink? How often do you clean your car?

I never clean either ;)

Don't follow the argument, I don't have a car for almost 10 years but when I did I used to clean it every 4-8 weeks, my kitchen's sink gets cleaned every week at least once.

The water in your home isn't as high in mineral content, as present in the atmosphere.

Stainless steel is designed to resist rusting from common minerals in fresh water. Citric acid, for example, is happy to stain your stainless steel.

Any ground water will have more minerals than wain water. For example, the water delivered to my house has 450-550 mg/l TDS. A quick search shows that is about 10x higher than rain water [1].

[1] https://www.chaitanyaproducts.com/blog/rainwater-healthy-com...

It's probably not rainwater that's causing the rust. It's the water from the pavement, which does have higher mineral content, and might have corrosive substances, such as salt.

My kitchen sink also doesn't get salted during the winter, the roads do. I wonder if someone at Tesla forgot that some areas rely heavily on salt to keep the roads ice free during the winter.

You don't use salt when cooking? :D

The concentration of salt in your cooking equivalent to the salt on the roads would make your food inedible.

Woah! I had no idea they were pumping groundwater into the Capilano Reservoir. Thanks for the heads up

Isn't rainwater slightly more acidic than ground water?

Rain water - sure. However rain water falls on the road, mixing with any minerals deposited on the road.

We use rain water extensively in NZ tho

But as others answered - it's likely pitting from other sources, not elements themselves

Choosing a different grade of stainless steel may buy you more corrosion resistance but the other properties may suffer (e.g. strength).

The most rust-resistant grades of stainless steel have lower tensile strength and hardness, and work-harden in a way that makes forming them a bit more expensive.

For example, your kitchen sink might be made out of 304 or 316 stainless steel - but your kitchen knives are more likely to use 440C which is less corrosion-resistant, but will hold an edge a lot better.

It also helps that you're not whacking road salt into your kitchen sink at 70mph.

Is there a safe speed to whack salt onto my kitchen sink? Most I've done is 55mph and it felt unstable.

If you leave wet steel wool in a stainless-steel sink, the sink will "catch" rust, too.

Regurgitated advice from metalworkers I learned from:

If you're using a grinding wheel or brush to buff stainless, make sure the tool hasn't been used on regular steel or iron, and that the part of the tool that contacts the stainless is itself neither rusting nor rustable, because even a speck of iron will "seed" rust in stainless.

Thanks that's interesting. I've seen this exact thing happen with stainless steel eating utensils (commonly called "silverware" in the US for historical reasons despite being stainless steel). In a storage unit, I found some very rusty spoons and forks that were in a box with other rusty things. The conclusion I left with was "stainless steel can indeed rust" but I didn't know why, so this is nice to know!

If you really want to blow your mind, your "porcelain" bathtub can also rust.

Learned this the hard way when a cat started pissing in the tub. Between that and using bleach for cleaning, the enamel was eroded down to the metal casting. Then, rust.

Advice online will say no, that red shit is calcium and mineral buildup. That mostly happens in toilets. Unless you bought a tub in plastic or fiberglass, it may well be actual rust, especially if it reoccurs very quickly. Treat it accordingly before it drains through your floor.

Roads are among the worst conditions for corrosion. If you left your sink outside where it could be affected by salty sea spray, road salt or calcium chloride, with these chemicals sitting on the metal over time, it would also develop rust spots.

The Doha airport features a stainless steel roof; standard architectural stainless steel would be far too vulnerable to corrosion in this setting. They had to specify a duplex stainless steel with a special finish, and even so it requires regular cleaning and rust removal:

https://www.imoa.info/molybdenum-uses/molybdenum-grade-stain...

"Stainless steel" is only a relative term.

who would have thought that elon of all people would fail to 'let that sink in'?

Your sink isn't exposed to UV light, dust, mud, extreme temperature changes, etc. I don't know either way if any of those would have an effect, but it's not at all a clear analogy between a kitchen sink and an automobile.

Maybe my grill is a better comparison. UV light: check. Dust: check. Extreme temp changes: check, and more than a car to boot. Salt: check, there are giant crystals of kosher salt all over it.

You know what I think is the culprit, there must be fragments of regular steel/iron debris on roads that get kicked up and form rust spots like wet steel wool would. Rust is terribly penetrating and can easily stain SS or even porcelain.

Still, a few rust spots aside, I don't think these cars will be rusting out like a 1980's Civic.

Time to invest in Bar Keeper's Best Friend.

Or short companies selling hydrophobic trucks.

That's why it's called stain-less. It stains less. (But still stains.)

I guess that's just in line with "Full Self Driving".

All of yourself needs to do the driving in your stain less vehicle.

It’s called the “No Homers” club, we’re allowed to have one.

Such a great line!

I wonder why this innocuous light-hearted comment in appreciation of someone else's joke is getting downvoted?

I don't think I'll ever understand why people downvote on HN...

It's pointless noise. Twenty other readers likely also laughed to themselves about the line, upvoted and moved on. The commenter will know if their joke was appreciated with upvotes. Nobody needed an extra comment from the peanut gallery.

HN polices noise very hard, because the alternative is half the site is just the first comment thread from reddit that continuously circle jerks the same damn jokes.

People read sarcasm into the comment and/or didn't get the reference? It's a mystery.

Anyway, here's the clip: https://youtube.com/watch?v=W7rSYzbpA8k

If they wrote it "stain-less" then I would have the correct notion.

But the spelling "stainless" makes me think of words such as "peerless".

Yeah, homeless, fearless, childless, hopeless, endless - all mean "without X" not "less of X"

I didn't mean that it "staining less" is the correct formal definition, only that thinking of it as "stain less" rather than "stainless" is a more useful definition to keep in mind, as all steel will stain eventually the right conditions.

Maybe they should call it stain-fewer, since you're gonna get fewer stains but not no stains.

Many "touch less" carwashes operating this way.

> think of it as “stain-resistant”

Actually you can just think of it as was intended: “stain LESS”. As in, not “stain NONE”.

Or maybe even stain-less?

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