From reader Redrum:
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Put a magnet to the pieces in question. If it sticks its a 400 series stainless and will rust. If the magnet doesn't stick the metal has a higher Nickel content and is a 300 series stainless and that does not rust. Sheet Metal worker for 48 years Union!
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MrF responds:
I find I have three different types of stainless items. The very magnetic ones are the ones that have developed rust. Then there are some very slightly magnetic items, one of which is marked "stainless steel 18-10". These have not had any rust. Also I have some 60-year-old Revereware, the stainless part of which is completely non-magnetic. I guess that's the good stuff. Made in USA in the old days. I also have some stainless steel KitchenAid appliances. Oddly, the fridge and stovetop are totally non-magnetic, while the built in oven/microwave is of the "slightly" variety. Neither has rusted. I guess you sorted it out for me.

Other reader comments:

From reader G.:
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Stainless steel can rust. Usually, in the presence of salt water or chlorine. AFAIK, it's not a result of radiation. Most likely, it's changes in the very local environment of the steel. Also, cleaning stainless steel with "regular" steel can cause corrosion. See: https://www.polymersolutions.com/blog/why-does-stainless-steel-rust/

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From reader StormyOne
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A stainless steel product manufactured properly will not rust. A product called 'stainless steel' that shows rust, was improperly manufactured with impurities.
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From reader P.:
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I've done a lot of reading, so take what I say with some salt.

But there are many types and alloys of what we call 'stainless' steel. Some are more stainless than others. No such thing as forever stainless perfection.

So after a very long time, even hi-quality stainless will begin to oxydize.

Then there is the recent decades, where profits are down and the use and production of cheaper steel products, enter the picture.

Money and costs are a big factor. Save money and buy low quality, or pay five times as much for high quality steel (if you can find it).

Real life sucks don't it?
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From reader C.:
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How odd?

things that rust?
something tells me not so good

I'm pondering more on that

I know this may sound odd to you

are humidity and humility
connected

what was and what may be not so
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