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Oct 2, 2010 01:32 PM

Will a magnet stick to/be attracted to stainless lining in a copper pan?

Anyone have stainless-lined copper they can test on?

Trying to determine whether the lining is steel or tin... how to tell?

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  1. Not all stainless steel is magnetic.
    That said, the stainless linings in my Mauviel and Falk bits are slightly magnetic, but not nearly so much as cast iron.

    One fairly good way to tell if the lining is tin is to look at the rivets holding the handles on. If the rivets are copper, then it's most likely a tin lining. Otherwise it's stainless lined, or a copper-plated stainless or aluminum pan. Some really old pieces were lined in silver, but they're rare enough that you're unlikely to encounter them.

    1. If you have cooked with it 3 or 4 times and you have dark patches or a generally uneven surface, it's tin. If it's nice and shiny all over, it's stainless steel. Also, tin is applied by hand, so if you see what looks like brush marks in the coating, it's tin. If it looks perfect (like the inside of a SS pan), it's stainless.

      1 Reply
      1. re: Zeldog

        Stainless linings usually look wire brushed, with the marks in perfectly concentric circles.

      2. It really depends on the stainless steel. For example, 18/10 and 18/8 stainless steels are not very magnetic, while 18/0 is. Most copper cooking lined with stainless steel is probably made of 18/10 and 18/8.

        1. Stainless steel is an alloy of iron and chromium with diminimus quantities of other elements, mostly carbon in the compound, but it is always subject to magnetic force because it is at least 85% ferrous. Do the magnet test.

          11 Replies
          1. re: Veggo


            It does not work that way. It isn't like 85% iron is 85% magnetic. A small amount of nickel will disrupt the crystal structure making the stainless steel essentially non-magnetic.



            1. re: Chemicalkinetics

              Nickel actually has one of the lowest Curie temperatures. I used a nickel alloy in a thermomagnetic motor I invented. I will be happy to discuss chemistry and physics with anyone off-board, I'm easy to find.

              1. re: Veggo

                "Nickel actually has one of the lowest Curie temperatures."

                What does nickel having a low Curie temperature has to do with anything here? Are you actually suggesting that nickel makes stainless steel more ferromagnetic?

                There are ferritic stainless steels and there are austenitic stainless steels and others. Austentic stainless steels are essentially non-magnetic because of their faced centred cubic crystal structure.

                "All austenitic grades have very low magnetic permeabilities and hence show almost no response to a magnet when in the annealed condition"


                "Alloying the stainless steel with elements such as nickel, manganese, carbon and nitrogen increases the likelihood that the alloy will possess the fcc crystal structure at room temperature."


                1. re: Chemicalkinetics

                  You are funny. The topic is magnetism, and you alone mentioned nickel, which has remarkable properties.
                  To the OP's question, a magnet will "stick" to stainless steel.

                  1. re: Veggo

                    I mentioned nickel because nickel is in austentic stainless steels which are the popular stainless grades in cookware. You mentioned Curie temperature. You want to explain how Curie temperature has to do with cookware here?

                    A magnet will only stick to some stainless steels, not all. Go get a high grade 18/10 fork or spoon, and get a refrigerator magnet and you won't able to stick them together.

                    1. re: Chemicalkinetics

                      I'm still owed a refrigerator magnet from The Style Invitational of The Washington Post.

                          1. re: Veggo

                            What a great thread this turned out to be! So much more than one could hope for. Veggo & ChemK - what an interesting, lively discussion. :) Makes me feel smarter just reading it.

                        1. re: Veggo

                          Follow up: The Empress from The Wash Post saw this thread and contacted me this morning to make right on the missing magnet. I had no idea she is a fellow hound. All's well that ends well.

            2. Well, this may be a fascinating thread, but it's "threadus interruptus" to me. What happened to the (disputed) answer to your OP question?

              25 Replies
              1. re: kaleokahu

                Back on topic, stainless alloys may have reduced magnetic properties, but nearly all will have some. A good 95% accurate test is with a strong magnet, not the refrigerator kind. Also, steel and tin resonate sound differently. You can test a known tin and steel pan with a tap from a metal spoon, and observe a difference in pitch and duration of resonance and timbre, but this can vary with the dimensions and thickness of the pan and other factors and also requires a good ear.

                1. re: Veggo


                  I worked with high field magnets like those superconducting 9.4 Tesla magnetic for 7 years. Yes, you are correct that in a very high field environment you can feel a pull from these nonmagnetic stainless steel. Even then, the forces applied on a magnetic stainless steel vs a "nonmagnetic" stainless are very different.

                  For every day kitchens, I really don't think people will have acess to these high field magnets.

                  1. re: Chemicalkinetics

                    True, and non-magnetic ferrous alloys generally have applications more exotic than for use in pots and pans. An example is the small gears in expensive mechanical movement watches, so that they are not affected by the electromagnetic fields of induction ranges or aircraft instruments.
                    As I recall, a frog was magnetized in the Tesla, a very expensive and energy consuming procedure, and actually floated weightlessly in a coil much stronger than the gravitational force.

                    1. re: Veggo

                      So, for folks with access only to a refrigerator magnet, testing their copper pan's lining with it isn't going to tell them anything, right? Final answer?

                      1. re: kaleokahu

                        I would suggest a hobby store for an inexpensive magnet of sufficient strength to confirm the pan's interior, as I mentioned, with 95% confidence. I think that is the best you can do. The donut shaped magnets about the diameter of a half dollar and about 1/4 inch thick have a pretty strong field as you will see, and you may come across a bar or horseshoe magnet in a toy store.

                        1. re: Veggo

                          Hmmm... Coincidentally, today I received an old-style (but brand new) kitchen timer with exactly that 1/4"-thick Kennedy-half-sized ring magnet glued to it's back, and the thing barely clings to my enameled steel range. I'll try it on my neighbor's Mauviel stainless pan and see...

                          1. re: kaleokahu

                            And if you try that magnet on a 18/10 stainless steel fork and spoon, you will not feel anything (unless you are very sensitive).

                          2. re: Veggo

                            You can pick up a rare earth magnet at a reasonable price. Neodymium are quite reasonable, while samarium-cobalt are a bit on the pricy side for such a simple task. Any hobby or craft store should have a neodymium magnet for a couple of bucks or less, if you can find them individually packaged.

                            1. re: mikie

                              And these will stick to ANY SS?

                              1. re: kaleokahu

                                Not any, but most. 95%. I'm sorry I have lost cred with you. I wish I could lend you my 220 volt electromagnet that would suck in you pan from a foot away, unless it is tin. Permanent magnets have limitations. Electromagnets...levitate trains, and frogs. But if you get the slightest tug with your magnet and pan, it is steel and not tin.
                                Tin has it's own set of unusual properties beyond the subject here, so I won't mention solder's melting point.

                                1. re: Veggo

                                  No loss of cred here, we just kept going off on (very interesting) tangents. I get it now; IYO: (a) any perceptible tug=game over. (b) No perceptible tug with a good magnet=still 5% chance it's SS.

                  2. re: kaleokahu

                    My take from this discussion is that:
                    - if a household magnet is attracted to the lining, then it is SS, not tin.
                    - if there is no perceptible attraction, the lining could be either tin, or a common non-magnetic SS.

                    If you want push the magnetic test further, test your magnet on other common stainless steel items. While my knives are magnetic, most of my SS sauce pans and mixing bowls are not - except for the bases of several new induction-ready pans. Then go buy a super strong magnet, and repeat the tests. If it sticks to 18/10 pans, it may also react with a thin 18/10 lining. If still no reaction, then more likely than not the lining is tin.

                    From an industry source:
                    "nswer: There are several "types" of stainless steel. The 300 series (which contains nickel) is NOT magnetic. The 400 series (which just contains chromium and no nickel) ARE magnetic." 18/10 is in the 300 series. 300 series is more corrosion resistant than 400.

                    Or, you could use one of the appearance tests.

                    1. re: paulj

                      To me, magnetism has always been the magical confluence of physics and the early stages of romance. It is so hard to tell if she likes you back, and she doesn't want to tell.

                      1. re: paulj

                        Knives are magnetic because even the so called 18/10 knives are not entirely made of 18/10. Do you have a set of 18/10 flatware? If you do, you will notice your forks and spoons are not magnetic. As for the knives, the handle is not magnetic, but the blade is.

                        1. re: Chemicalkinetics

                          I had in mind my cooking knives (usually with plastic handles), the sort that I keep on the magnetic bar rack. My flatware is also magnetic.

                          1. re: paulj

                            :) For cooking knives (knives for cutting up raw meat and vegetable), you definitely do not want a 18/10 stainless steel. 18/10 stainless steel is a horrible steel for cooking knives. As for flatware, most flatware are made of 18/0, 18/8 or 18/10 stainless steel. 18/0 is the cheapest and is very common among inexpensive flatware. Those are magnetic. However, if you have those $200 for 4 flatware sets, then they are probably 18/8 or 18/10


                            1. re: Chemicalkinetics

                              I just happen to have some samarium-colbolt rare earth magnets, about 1" dia. and 1/4" thick. I don't have a stainless lined copper pot to test. However, I tested just about everything in the kitchen. Some stainless items are much more magnetic than others. I tested flatware, Lenox, 18/8 if I remember correctly, I could pick up the flatware with the magnet. Tested some measuring spoons from WS stamped 18/10, still magnetic, but not as much as the flatware. SS pots, spatulas, spoons, tongs, etc. there was some attraction to everything.

                              1. re: mikie

                                Hi Mikie,

                                I agree. Some stainles steels are more magnetic than others. What you may have also realize is that not even all 18/10 stainless steels are the same. My 18/10 stainless steel measuring cups made by AMCO is noticeably magnetic. My Calphalon 18/10 sauce pan is slightly magnetic, while my 18/10 Oneida flatware are not magnetic at all, except the knife blade. Depending how the 18/10 is treated after the first annealing, it can convert back to body center crystal structure and then becoming more magnetic. Now, as you increase the magnetic field of your magnet, you will start to feel more and more including everything stainless steel. This is in fact true for any metal. At high enough magnetic field, almost everything is magnetic.

                                You can even magnetize a frog like this:


                                a water droplet, a mouse...


                                Tin is also not nonmagnetic...

                                1. re: Chemicalkinetics

                                  "This is in fact true for any metal. At high enough magnetic field, almost everything is magnetic. "

                                  This may be too technical for this discussion, but I think the idea that everything can be "magnetic" needs clarification. Most materials are ferromagnetic, paramagnetic, or diamagnetic.

                                  Ferromagnetic -- what we think of as normal "magnetic," as in iron. Ferromagnetic materials respond strongly to magnetic fields and can retain them internally (i.e., become magnets themselves). Electrons tend to orient themselves parallel to the field and settle into a lower energy state.

                                  Paramagnetic -- these materials will respond noticeably only to strong magnetic fields. They have free electrons that will respond to a field, but they have to be forced into that orientation. Thus, the material will not appear magnetic once the field goes away.

                                  Diamagnetic -- all materials are diamagnetic to some extent, but diamagnetic behavior is only really observed in materials that aren't ferromagnetic or paramagnetic. Diamagnetism is the tendency of a material to be repelled by a magnetic field (and to weaken it). No free electrons are available to orient themselves with the field.

                                  In strong magnetic fields, the diamagnetic property can be used to push things in particular directions, hence the levitation of a frog or water droplet or mouse. I wouldn't refer to that as "magnetizing" a frog, though, because if anything, it's the frog's strong tendency to not be magnetized that causes it to be repelled by the field and thus levitated.

                                  1. re: Chemicalkinetics

                                    Aren't we getting to the level technical detail where we should be using terms like ferromagnetic, paramagnetic, and diamagnetic?

                                    "Ferromagnetic materials have a large, positive susceptibility to an external magnetic field."
                                    "Paramagnetic materials have a small, positive susceptibility to magnetic fields."
                                    "Diamagnetic materials have a weak, negative susceptibility to magnetic fields."

                                    As best I can tell, copper is diamagnetic, tin has both paramagnetic and diamagnetic forms. 300 series stainless steel is largely paramagnetic, but may develop some ferromagnetism.

                                    With household magnets you can distinguish between ferromagnetic and non-magnetic. You need strong magnets to identify para and dia magnetism.

                                    1. re: paulj

                                      Yes to both athanasius and paulj. Yes, I agree with Paul. Tin can take on two forms. The way I see it is that ferromegnet react very strongly to external field and can retain a certain level of magnetization after the external B field is removed. It is what we usually refer as magnetic, such as iron and ferritic stainless steel. Paramagnet are parrallel to B and diamagnet is opposite to B.

                                      In paramagnetism, the external B field exerts a torque on the magnetic dipole moment:

                                      N = m X B. The important point is that the torque is pushing the dipole parallel to the B. This is especially strong for odd free electron.

                                      In diamagetism, the B field reacts to the orbital dipole moment. So the change in M is opposite is to the direction of B. More like a shielding reaction. This is usually for even number of electrons.

                                      Now, my E&M physic book (Griffiths) classifies paramagnetism as part of magnetization.

                                  2. re: mikie

                                    I started thinking about what I might have to test per the OP. Ha! My mother's old Revere copper bottom sauce pan. Starting with the rolled rim, there was a very strong attraction, the side wall had some attraction, but the bottom (from the stainless inside) appeared to have no attraction that I could detect with the samarium-cobolt magnet. All of whigh means, that even with a relatively expensive and powerful magnet, you are not going to be able to know for certain it a copper pot is SS lined or tin.

                                    1. re: mikie

                                      Mikie, thanks for your field testing!

                                      1. re: dost

                                        Yeah, thanks. Brought us right back where we started (magnets won't stick to all stainless). But emphatically so. And with pith.