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Have I been poisoned by the copper pot I just bought?

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lazycook Jan 6, 2010 09:42 AM

Yesterday I bought a used pot in a Goodwill thrift shop for $10 that I thought was a copper coated on the outside stainless steel pot, but after reading about copper pots on this board I now think it is a stainless steel or tin lined copper pot, as it is very heavy for its size. There is no brand name on it. The pot seems to have been made by spinning as the interior has small grooves in it, and looks high quality by its intricate design and construction.
My worry is I cooked a mixture of broccoli, carrots, and snap peas in it and ate about half of it and left the rest sitting in the pot for several hours. When I looked at it later the interior of the pot had turned a blue violet color where it was in contact with the vegetables. What could this be, and is it poisonous and should I throw this pot out?
The exterior of the pot also is covered with what I think is lacquer. I scrubbed the pot with barkeepers friend and a steel wool pad and got the violet colored tarnish off the inside and most of the lacquer off. I also tried to burn the lacquer off by putting the empty pot on the stove with the gas turned up high but quickly shut it off when the outside copper part of the pot started to turn blue violet colored too.
Is what happened normal and does one have to season copper pots, or maybe is the coating on the inside too thin, although I can't see any copper showing on the inside?

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  1. Chemicalkinetics RE: lazycook Jan 6, 2010 09:58 AM

    Lazy,

    First, copper poisoning is a real thing, not a theory like aluminum. Second, copper posioning (for normal people tends to be acute, not chronic like lead poisoning. Third, copper poisoning usually lead to abdominal pain, nausea and diarrhea.

    I don't think you have copper poisoning because you do not see any signal of copper. If the pot is lined with stainless steel, it is not unusual for stainless steel to turn some kind of "rainbow" or "bluish" color when stainless steel is overheated. Maybe that is what you meant by violent color.

    2 Replies
    1. re: Chemicalkinetics
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      lazycook RE: Chemicalkinetics Jan 6, 2010 05:07 PM

      I should clarify my original post. I don't feel sick after eating the food. I just want to know if I should stop using this pot because after the first time I used it part of the interior tarnished to a rainbow, color, mostly blue-violet when I left some of the food sitting in the pot for several hours. Is this a sign of a defective coating? As I said, I bought this pot in a thrift shop used, although it looked like it had only been used a few times. Has anyone else ever had the stainless steel or tin coating turn to a blue-violet color after using a pot. The handles appear to be brass, and the rivits stainless. Could this be a silver coated pot, since silver sometimes turns a blue-violet color. The pot does look like it was expensive. There is also a frying pan that looks like it came from the same manufacturer still in the thrift shop also for $10, but one side is dented in, which makes me think it is a soft metal like copper. It looks like it could be easily straightened out with a rubber mallet, but would that damage the coating? Should I buy it too or stay away?

      1. re: lazycook
        Chemicalkinetics RE: lazycook Jan 6, 2010 05:39 PM

        Hi lazy,

        As mentioned in my original response, it is very normal for stainless steel to turn into that rainbow and bluish color. In fact, I mentioned the word "rainbow" before you did.

        I will give you a few other sources, so you know this is not just my opinion:

        This is normally caused by overheating or exposure to high heat or when the burner is wider than the pan you're cooking in."

        http://calphalon.custhelp.com/app/ans...

        "If your stainless steel pans develop a rainbow hue on the inside bottom, it usually means the heat was too high."
        http://www.abouteating.com/Stainless_...

    2. Zeldog RE: lazycook Jan 6, 2010 07:55 PM

      Photos would help, but this is a mystery to me. Brass handles and rivets suggest a copper pan. On the other hand, "made by spinning" with "small grooves" sounds like a machined surface, but no copper pan I'm aware of is made like that. Violet discoloration suggests a steel interior, but after just one use sauteing veggies? Tin lined copper will discolor on contact with some foods, although I would describe it as black rather than violet. Maybe that's what you have, in which case, don't worry about it.

      These grooves. Are they perfectly circular and even like they were made with a machine, or rough like you wiped a rag over the surface in a circle? If the latter, you probably have a tin lined pan.

      1. cowboyardee RE: lazycook Jan 6, 2010 08:16 PM

        I also believe you're noticing a stain that's very common to stainless steel or stainless-lined pots.

        http://chowhound.chow.com/topics/609807

        As far as I know, this type of stain is completely harmless. You could leave it there and it would probably fade and cause you no problems.

        However, if you decide to scrub it off, use a minimally aggressive abrasive (perhaps, the Barkeepers Friend but not the steel wool) and be careful. If your pot is indeed copper lined with stainless, you don't want to wear through the lining because unlined copper can cause you problems. (i think it would take A LOT of work to get through stainless lining to the copper anyway - but no harm in being careful).

        5 Replies
        1. re: cowboyardee
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          lazycook RE: cowboyardee Jan 6, 2010 10:01 PM

          The sides on this pot are not straight up and down, instead the widest part is about half way up, with the bottom and the lid end about an inch smaller in diameter. That is why I think the pot was spin formed, as it couldn't be just stamped out like that. The grooves are very shallow, just enough so you can see many microscopic but evenly spaced lines, concentric circles on the bottom. The pot lid is very heavy too.
          As I said, I have already removed the interior stain with barkeepers helper and a steel wool pad. So I guess the concensus is this pot is safe to use?
          BTW, one can buy 96% tin, 4% silver solder for $61 a pound or $6.40 an ounce. Has anyone ever tried re-tinning a pot themselves?
          I searched through several copper pot sellers websites and don't see a single pot that looks like this one so I am guessing it must have been a very rare expensive brand. All the ones I see have straight sides or uniformly tapered sides, not convex sides like this pot has.

          1. re: lazycook
            Chemicalkinetics RE: lazycook Jan 6, 2010 10:13 PM

            Ok, next time, do not use steel wool.

            1. re: Chemicalkinetics
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              sandy1456 RE: Chemicalkinetics Oct 24, 2010 09:22 AM

              Hi, I am new to Chow... and have a question about copper pots. i just bought a revere ware 12"skillet, used ,at an Estate sale, but noticed, after getting it home, that it has one small area (about the size of a dime) that is pitted on the inside of the pan... kind of a round area... the pits are black, and I can not get them clean. i do not see copper showing through though. Is it safe to use this skillet? it seems fine otherwise. I also purchased a large copper sauce pan that is copper with an iron handle, marked lewis & conger NY... the inside is very grey, and will not clean up... but... no copper showing through. Is this one safe to use? Thank you so much for any response. I have searched the net for these answsers... only to keep finding myself on this website. THANK YOU!!

              1. re: sandy1456
                Chemicalkinetics RE: sandy1456 Oct 24, 2010 10:03 AM

                Copper poisoning is unlike lead poisoning. For most healthy adults, we have the ability to clear copper from our body. Children are different. On the other hand, if a person has a genetic disorder like the Wilson's diease, then this person can be severly poisoned by copper.

                http://en.wikipedia.org/wiki/Wilson&#...

                Many copper cookwares are lined with tin or stainless steel. Tin lining tends to thin out over time and copper can eventually show through. I think it is rather difficult for copper to show through a stainless steel lining.

                The Revere ware that I know of are stainless steel cookware with a very thin layer of copper, so I doubt the copper can show through the cookware without the cookware first crack open.

                http://eclecticauctions.com/wp-conten...

                You can probably remove the pitted area with Bar Keeper's Friend.

                I don't know about Lewis and Conger, but the internet search shows some of these are lined with zinc.

                http://www.worthpoint.com/worthopedia...

                Zinc has a melting point ~420oC, which is much higher than tin (232oC), so the zinc lining probably is fine, but I cannot be absolutely sure about it.

                1. re: sandy1456
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                  ThreeGigs RE: sandy1456 Oct 24, 2010 12:04 PM

                  The pits are rust. Yes, rust. Search chowhound for 'passivation layer' to find some posts about it. You will have to do some heavy-duty scrubbing or sanding to get rid of the rust pits completely, and then all will be well.

                  Your other pot sounds like a tin-lined copper pot. Read up on care for your tin-lined copper on here and you'll be well served by that pot.

          2. Sid Post RE: lazycook Oct 24, 2010 04:55 PM

            It sounds like you have a "lined" copper pot. Most likely it is lined with Tin which you can melt if you overheat your pot. If it is a stainless steel lining, then you have nothing to worry about unless you scrub through the lining or heat it excessively. The Bluish/Violet tint is pretty common on Stainless steel when you overheat it.

            At this point if your pot poisoned you, you would already know it and most likely would have received professional medical care already.

            Without pictures, it's hard to know what you really have. You might want to read up on tin lined and stainless steel lined copper cooking to put your mind at ease.

            1. b
              bellybones RE: lazycook Oct 24, 2010 05:51 PM

              I have the perfect solution to your dilemma - throw the $10 pot in the trash.

              2 Replies
              1. re: bellybones
                Sid Post RE: bellybones Oct 24, 2010 09:58 PM

                Or recycle the copper for $$$ if that's legal where you live. With all the meth-heads in Arizona steeling copper wire from houses and utilities, you can't recycle for $$$ as a consumer any longer.

                1. re: bellybones
                  kaleokahu RE: bellybones Oct 25, 2010 03:11 PM

                  NOOOOOOOOOOOOOOOOOOOOOOOOOO, don't throw it out if you haven't already! Please post photos first. You might have a phenomenal value on your hands. I found an UNUSED Mauviel fish poacher at a garage sale for $25. There are deals out there.

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