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Is there a test for stainless steel?

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Kittish

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You can find a lot of utensils and equipment sold as "stainless steel" that isn't actually. I learned this first hand, bought what I thought was a set of stainless utensils and the one I used to stir my lye water.. well- see for yourself.




This discoloration is even after washing the spoon with dish detergent. The shiny surface is just GONE where the spoon was immersed, along with the black spots and streaks that won't come off. This change in appearance happened the very first time I used the spoon. Yes, I tossed that batch of water and mixed up fresh.

My lye pitcher is also stainless steel, but the actual real deal. I can't see ANY difference in it after a couple of uses, no residue or color or surface changes.

So, my original question- is there some easy, reasonably reliable way to test whether stainless steel really is or not, aside from mixing a batch of lye water in or with it? (I don't consider magnet tests to be reliable- most older stainless steel isn't magnetic but a lot of new stainless is, especially cookware for induction cooktops.)
 

Viore

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I think stainless steel will stick to a magnet, and aluminum won't. Sorry, that's the only test I know.
 

Susie

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I understand that what I am about to say is going to cause controversy, but I use a magnet at the store. If it does not stick, I won't buy it. There is a "stainless steel" that is non-ferrous, but I get the black spots every time I use one of them.
 

Kittish

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I just went back and checked, and most of the stainless steel implements in my kitchen are not magnetic. These are all items that I know are actually stainless steel, including my lye pot.

The spoon that discolored the first time I used it WAS magnetic. The rest of the set that spoon came from displays varying degrees of magnetism across the utensils.

From a bit of searching, whether stainless steel is magnetic or not depends on the alloy. The more common alloy is not magnetic.
 

BrewerGeorge

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"Better" stainless is typically less magnetic in cookware. Newer pots and pans made for induction typically have sandwich bottoms of regular steel so induction functions, but their sides usually won't be magnetic.

There are hundreds of types of stainless steel. The most common for cookware and cutlery will be 304 (including 18/8 and 18/10) and 316 (also called A4). Most common is 304 which is just slightly magnetic. Alloy 316 is second most common and does not respond to magnets at all. You can also find cheaper cutlery in 18/0 (which is a 430 series without nickel). It is the most magnetic and least resistant to corrosion. The 430 would typically be used for things like the front of a stainless fridge or a kitchen prep table, but recent years have seen its increasing use in very inexpensive cutlery as well.

Any 300 series should be completely resistant to lye. I'm not sure about 18/0, but it is definitely more likely to rust so it could be more likely to be affected by lye.

However, looking at your pictures again, that may not actually be corrosion but electroplating. What was the container the spoon and lye were sitting in while that happened? The stainless lye pitcher you mentioned? Did anything unusual happen during the process such as sitting a long time in the lye without touching the side of the container?

..
The spoon that discolored the first time I used it WAS magnetic. The rest of the set that spoon came from displays varying degrees of magnetism across the utensils.
...
I missed this before replying. If it's strongly magnetic, that spoon is 18/0 - the cheap stuff.
 

Kittish

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BrewerGeorge- I'm kind of leaning toward thinking that the spoon is just plain, ordinary steel or maybe the 18/0 you mentioned, possibly chrome plated so it looks all smooth and shiny like good stainless does. IOW- fine for food (except this one spoon) but not so great for making soap.

The spoon was in the water in the pitcher when I added the lye, but I took it out as soon as I brought it inside. I know it's not the best practice, but I mix my lye water outside (because reasons), and it was night so my light was limited so I didn't see the discoloration until I got it back inside and pulled the spoon out. There weren't any visible particles or bits in the water, it was nice and clear. I can't feel any lines or ridges where the discoloration begins. That batch of water got poured down the drain and flushed for about 5 minutes, then I washed the pitcher (examining it closely) and made a new batch of lye water.
 

wetshavingproducts

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So, without giving a metallurgy lesson, here's what you need to know about "stainless" steel. The only thing that makes it stain less than regular carbon steel is the inclusion of chromium. Modern stainless also contains nickel. Stainless used for cutlery is still magnetic, but has a high carbon content and low chromium content. 440, which is decorative contains a lot of chromium & nickel, cannot be hardened (ie makes for a bad tool) and is not magnetic.

I have no idea if regular steel reacts, but nickel does not. Chrome itself actually will corrode over time, but very slowly with caustic solutions. That said, 18/10 or 440 should be fine. Honestly that spoon doesn't even look bad. Just looks like it took the finish off.
 

BrewerGeorge

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So, without giving a metallurgy lesson, here's what you need to know about "stainless" steel. The only thing that makes it stain less than regular carbon steel is the inclusion of chromium. Modern stainless also contains nickel. Stainless used for cutlery is still magnetic, but has a high carbon content and low chromium content. 440, which is decorative contains a lot of chromium & nickel, cannot be hardened (ie makes for a bad tool) and is not magnetic.

I have no idea if regular steel reacts, but nickel does not. Chrome itself actually will corrode over time, but very slowly with caustic solutions. That said, 18/10 or 440 should be fine. Honestly that spoon doesn't even look bad. Just looks like it took the finish off.
Are you sure you're not confusing 440 with 316? 440 is the hardest stainless and is magnetic.
 

Kittish

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Honestly that spoon doesn't even look bad. Just looks like it took the finish off.
Without knowing exactly what it is actually made from, I don't feel comfortable using it for soap or food in its compromised state. I've relegated it to my gardening tools, it's great for scooping potting soil when I repot something (just repotted my pineapple, in fact). And I don't care if it rusts for gardening with.

Set of stainless bowls I got appears to be actual stainless, mixed up a batch of soap in the biggest one last night and after cleanup it's still mirror bright and perfectly smooth.
 
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