Should I be concerned about heavy metal poisoning when I use said chamotte stone in an electric home oven? The dough would be placed directly on the hot stone.

I didn't want to buy a dedicated Baking Stone, because the dimensions didn't match as well as the prices seemed to be too high. So I picked up a chamotte plate from a hardware store.

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    I wonder if you can chip a piece off the chamotte plate and have it tested for heavy metals. I know you can get soil samples tested for heavy metals at fairly reasonable prices. – csk Mar 2 at 20:05
  • that's worth the consideration. i might have a friend or two who has access to a specrometer. but then again, difficult times right now – Schelmuffsky Mar 3 at 10:59
  • Maybe this is a stupid idea, but would putting a layer of aluminum foil on top of the stone still let it work? If it's heat you're looking for, it should work fine. – Devyzr Mar 3 at 18:37
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    @Devyzr : you're right, that wouldn't influence heat transfer. but you still wouldn't know if there is anything inside the stone that would evaporate in the hot oven. besides: the stone would no longer be able to extract liquid from the dough – Schelmuffsky Mar 4 at 8:01

General consensus is that you should not use something that is not food safe for cooking.

And in particular something made for construction/building, it probably contains lot of non-food safe chemicals, and they are probably not obligated to list the ingredients; so you do not know what is inside.

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    Chamotte is used in some baking stones, but you don't know what else is in there. – GdD Mar 2 at 13:37
  • @Max : You're right. I'll probably have to return them. Unless customer service of the store can give me a positive confirmation of the food safety of the plates. I could imagine that the stones have some safety standard since chamotte plates of this size are often used for the baking surface in outdoor wood fire ovens, among other things of course. – Schelmuffsky Mar 2 at 14:09
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    I got the info from the store: they state that the chamotte stones are not food safe. – Schelmuffsky Mar 3 at 11:03
  • Well, go with the store's info then. They'll know better than anyone. – FuzzyChef Mar 3 at 18:23

I'm going to disagree with Max and say that I would use it. My current baking stone is a slab of cordierite ceramic made for ceramic kilns, the same material many baking stones are made from. I got it because custom-cut kiln shelf is less expensive than a custom-cut baking stone.

However, there is a serious risk there. For both chamotte and cordierite, there is the possibility that the material contains traces of toxic heavy metals, particularly since they are good at absorbing metals from the environment. Supposedly, ceramic materials sold for food preparation are tested to make sure that they don't contain any, whereas ones used for other purposes are not.

My personal experience, though, is that (at least in the US) testing practices around things like baking stones are extremely lax, and I made the assessment that I was not reducing my risk by using a stone made "for cooking". I cannot back that with any science, though, so this is a personal assessment of risk. And if you're cooking for someone with elevated risk (such as someone with kidney disease), even the smallest risk isn't worth it.

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    good point! it's a good thing to ask yourself what's actually behind a certificate. – Schelmuffsky Mar 3 at 11:09
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    Yeah, I looked into one brand that claimed to test theirs, but nowhere on the website did it say HOW they tested them ... which suggests that they don't. – FuzzyChef Mar 3 at 18:22

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