I am shopping for some metal pans and beakers for use on my magnetic stirring hotplate. I do not want to block the magnetic coupling of the stir bar. The question is which common alloys are compatible? Is the compatibility essentially binary or are some materials weakly compatible?

I assume aluminum is fine because the hotplate is made of some type of cast aluminum, but I am uncertain of the effect of alloy or cold working. My ferro-magnetic stainless steel and carbon steel pans are not compatible. But how about austenitic stainless steels[non-magnetic, 304/316], copper, or brass? Unfortunately I don't have any known samples on hand to test.

Glass is ok in a pinch, or when chemical reactivity is an issue, but for simple heating baths it is a poor conductor, more fragile, and in larger sizes much more expensive than metal. (And ease of sourcing, I am near a commercial kitchen supplier and a scrap dealer with all shapes and material stock pots but I need to ship lab supplies.)

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    $\begingroup$ 304 will be better than 316 because 316 can have fairly high ferromagnetism when cold worked. Cold worked 304 can also pick up some magnetism. Probably need to take magnet with you when you shop for a beaker $\endgroup$ Commented Apr 13, 2022 at 16:49
  • $\begingroup$ Yeah the empirical method is probably the practical solution. Still leaving the question open so people can add data, maybe I'll post what I find and make it a wiki. $\endgroup$
    – Max Power
    Commented Apr 21, 2022 at 22:21


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