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Utensils for kitchen

  1. Aug 16, 2007 #1
    I was buying some spoons and forks and knives made in China.
    Very nice and attractive design and it was written there stainless steel.
    After I was using them 1-3 times now I see a reddish-brown-colored under the so called stainless steel and I have no idea what is but I guess is copper and I am scarred copper can be poisonous and even fatal to organisms.

    Do you think is good to continue to use them ?

    Also if I will buy another how to know are better.
     
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  3. Aug 16, 2007 #2

    JasonRox

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    If you're concerned about products from China, why the hell are you buying them?

    Sure it said Stainless Steel, but you practical implied that you had doubts. But I guess you bought it because it was cheap. Money overrides everything.

    I would say buy some that are from Canada or the US. That should be good.
     
  4. Aug 16, 2007 #3
    No.

    The kind of stainless steel used in utensils in magnetic. Copper is not. Bring a magnet to the store.

    Also, try a magnet on the ones you have. They could be chrome plated steel, in which case the brown is common rust, and the claim you read on the package was actually just "stainless", and not "stainless steel". I would bet this is the case since copper should oxidize as a blue green crust.
     
  5. Aug 16, 2007 #4

    Moonbear

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    My guess is the reddish brown is rust. If they were cheap, it's unlikely they are solid stainless, but are just plated with it. When it got scratched enough, the exposed metal beneath started rusting.
     
  6. Aug 16, 2007 #5

    Moonbear

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    Ah, yes, that's most likely.
     
  7. Aug 16, 2007 #6

    FredGarvin

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    I'll give the manufacturer the benefit of the doubt and say that the material was chinced on the chromium. For steel to be considered a stainless steel a minimal amount of chromium as alloying element is 11%. Most likely they tried to get the bare bones minimum and were a little under, hence the rust. It's definitely not copper.

    I thought 18-8 was the common material for most utensils. It's one of the 300 series austenitic stainless which is not magnetic. The 400 series is magnetic though.
     
  8. Aug 16, 2007 #7
    I just tried out the 14 utensils (table knives, forks, table and tea spoons) in the drawer here and 12 out of the 14 stuck to the magnet, (this is a hodgepodge, I don't have a unified set) for whatever that's worth statistically. They're all rust and blemish free, and fairly old.
     
  9. Aug 16, 2007 #8

    mgb_phys

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    Most are probably stainless steel,
    The non-magnetic ones are either silver (common for teaspoons) or Nickel-silver (a copper /nickel alloy - nothing to do with silver) if they are old.

    Copper is toxic in large enough doses (just about everything is!) but very expensive saucepans are also copper.
    As someone sad the brown stains on the imported stuf is just rust.

    Stainless steel isn't the best material to make blades out of - you used to be able to buy carbon/tool steel knife blades before someone decided that it wasn't safe because of the rust. Oddly at the same time everyone started taking iron and mineral supplements.
     
  10. Aug 16, 2007 #9
    No, I'm sure they are just the non-magnetic stainless alloy mentioned by Fred Garvin. By "fairly old" I mean ten years or so. Had they been chrome plated non-stainless, the plating would have deteriorated by now. I'm familiar with the particular look of silver utensils and these are clearly not that.

    Rust in wounds gives you tetanus, no?
     
  11. Aug 16, 2007 #10

    mgb_phys

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    Nope - tetanus in wounds gives you tetanus! It's just that anny metal you cut yourself on in a farmyard is also liekly to be rusty.

    There are 3 main types of stainless:
    Austenitic, s highly corrosion resistant, tough and a bugger to machine but doesn't really sharpen well, we use it for making parts for marine enviroments. It's mostly non-magnetic ( except when we made a very sensitive magnetometer out of it).

    Ferritic is the most common, it's pretty resistant to corrosion, cheap and easiest to machine. It's magentic and is used for cutelry but isn't hard enough for a really good edge.

    Martensitic is the least corrosion resistant and brittle but is the hardest and holds an edge best, it is used for very high quality knife blades. It is magnetic. You can know do clever things to Martensitic to make it tougher and more corrosion resistant but that's expensive.
     
  12. Aug 16, 2007 #11
    Ah, I understand.

    Yes, I have a stainless folding knife that is probably the second kind because it doesn't take an edge for squat.

    I used to be a lathe and mill operator and machined the first and second kinds occasionally, and I hated them both. Give me aluminum or cold-rolled.
     
  13. Aug 16, 2007 #12

    mgb_phys

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    I'm an astronomer/optical engineer - we make a lot of stuff out of Invar, it's a 36% nickel ss with very low expansivity. But it's evil stuff to machine and eats drills and taps - I still have the scars.
     
  14. Aug 16, 2007 #13
    I had one run in with invar, and, yeah, I very much disliked it.
     
  15. Aug 16, 2007 #14
    Without spending an arm and a leg or two ,It is difficult to find anything for the kitchen that is not made in China. Sometimes it is just impossible at any price.

    A lot of their spoons ect. are nickle plated steel. The nickle wears off fairly fast.

    They are also cranking a lot of counterfeit name brand products.
     
  16. Aug 16, 2007 #15

    FredGarvin

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    I think you're going to have to sacrifice and donate your utensils so we can do cross section cuts and do a microscopy investigation. You can get 300 series to take a magnet but you have to do it on purpose. Do you live under really big electrical lines or have a distribution line running behind your utensil drawer?:tongue2:
     
  17. Aug 16, 2007 #16

    FredGarvin

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    Have you ever tried the free machining version of Invar?
     
  18. Aug 16, 2007 #17

    Evo

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    Has anyone tried ceramic knives?
     
  19. Aug 16, 2007 #18

    mgb_phys

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    Now they tell me :cry:
     
  20. Aug 16, 2007 #19
    I don't know what to tell you, Fred. I just remembered I had a bunch of odd stainless utensils I'd bought at the swap meet to make into arrow heads. I just dug them out and tried them as well, and only one out of 33 would not attract the magnet. I think you are overestimating the percentage of utensils that are made from non-magnetic stainless.
     
  21. Aug 16, 2007 #20

    mgb_phys

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    The only knives I can think of that would be made out of 300series stainless are dive knives.
     
  22. Aug 21, 2007 #21
    I have got a new set, made in Germany, Solinger.
     
  23. Aug 21, 2007 #22

    mgb_phys

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    I just tried my Solinger's they are very magnetic - as I said you wouldn't use 300 series unless anti-corrosion was more important than the blade quality.

    Edit- Oh sorry you weren't saying your Solingers were non-magnetic, I misread the thread.
     
  24. Aug 21, 2007 #23

    Astronuc

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    300 series SS are austenitic, while 400 series SS are ferritic.

    304 and 316 are probably the most common 300 SS in use.

    The kives in the Gunter Wilhem Professional Series Cutlery set are made with 440 SS. Other sites mention high carbon SS.

    Interesting - many dive blades are 304, 420 or 440, but now Ti-alloys and Co-Cr alloys are available. Taloniteā„¢ is a Co - 30Cr alloy similar to Stellite.

    Several steels and alloys are mentioned here - http://www.alphaknifesupply.com/bladesteel.htm

    I would caution against Ni-plated cutlery. Ni is relatively mobile and will get into the food.


    Tetanus is caused by a Gram-positive bacterium, Clostridium tetani. Several of this genus produce neuro-toxins, including Clostridium botulinum.


    I've used ceramic knives of either silicon nitride or silicon carbide. They work well.
     
  25. Aug 24, 2007 #24
    I am so tired to worry about many things.
    why do they sell toxic products and make us our living unsafe?
     
  26. Aug 24, 2007 #25

    mgb_phys

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    Don't worry, lots of stuff is banned that our grandparents used everyday of their lives. If everything that is now banned was so harmful you wouldn't be here.
    It's mostly to do with lawyers rather than science.
    A bit of rust isn't going to hurt you.
    Neither is a bit of dirt on your food.

    Antibacterial soap is probably going to wipe out humanity but thats another problem.
     
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