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https://www.youtube.com/watch?v=8RwP6ISf0GY

These were a recent purchase, so they had a very strong smell of "paint" out of the box. First thing I did was submerge them in water. It's obviously non glazed because you can see the air bubbles coming out from within the clay. I'm wondering if it's safe to drink hot beverages from this type of material or even drink from it at all.

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    Clay with a smell of paint? That would be a strong sign in itself not to use them for food, to me.
    – Ecnerwal
    Sep 13, 2023 at 13:02
  • @Ecnerwal I just attributed the smell to the matte glaze (or partial glaze) of pottery that usually goes away after you soak and let dry.
    – PrashanD
    Sep 13, 2023 at 15:17
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    Glaze (matte or shiny) has been through a kiln at temperatures that don't (certainly should not) leave anything behind that smells.
    – Ecnerwal
    Sep 14, 2023 at 0:40
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    We have at least one user who is both experienced in cooking and pottery, perhaps they can chime in.
    – Stephie
    Sep 15, 2023 at 13:34
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    No pottery glaze will have a smell.
    – FuzzyChef
    Sep 15, 2023 at 18:56

2 Answers 2

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Potter here, weighing in at Stephie's request.

What we see on video is sufficient to determine that the mugs are not vitrified ceramics. Vitrified means that the clay has been fired to a temperature where the silica in it turns to glass, making it waterproof. Generally speaking, you want most food-related pottery to be vitrified. Certainly those mugs are not safe to use in the microwave or the dishwasher.

Non-vitrified ceramics do have food uses, though. For example, a lot of traditional baking dishes are non-vitrified, because their underfired nature actually helps deter cracking. And in India, it's common to use very underfired ceramics in place of disposable cups; you just need to drink from them quickly, before they start to seep.

All that aside, there is no good circumstance under which any ceramic item used for food should "smell of paint". Any glaze on the pottery would have been through at least a 900C firing, and as such will have no smell at all. That points to some kind of paint or sealant being used on the mugs, and if that substance is not documented you have to assume that it might contain toxic materials. Also, if the vendor did not mention using sealant or paint, you have to ask what else they might not have mentioned, such as lead or cadmium in the clay itself.

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  • Do you think this method of cooking food in clay pots is safe? Does this fall in the category of non-vitrified pottery? recipes.timesofindia.com/articles/food-facts/…
    – PrashanD
    Sep 15, 2023 at 20:40
  • @fyrepenguin thanks, fixed
    – FuzzyChef
    Sep 16, 2023 at 22:02
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    Correct, those are exactly the kind of non-vitrified pots that are traditionally used for braising and baking. Note that, when cooking with them, there's generally some preparation steps such as soaking the pot, or coating the inside with something such as milk.
    – FuzzyChef
    Sep 16, 2023 at 22:03
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    Also, some of those types of pots have a glaze on the inside, which makes them water-resistant, but not water-proof.
    – FuzzyChef
    Sep 16, 2023 at 22:06
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Your video shows that the clay is not waterproof. This means liquid will be absorbed into the clay, which then can harbor mold and bacteria and contaminate food at a later time. This is why unglazed pottery is generally considered not food safe (with some exceptions for types of pottery that develop a closed, glass-like surface like porcelain). The temperature of the liquid will only influence the speed with which liquid gets absorbed, not the general principle.

That said, there are types of unglazed clay pots used for cooking, but they are typically heated so hot and for so long that food safety is ok (-ish, you still want to clean them meticulously and keep them dry to prevent mold), unlike drinking vessels, and the clay itself must be non-toxic, of course.

In short - if there are bubbles, there’s a potential problem with food safety.

Personally, I’d probably use the mugs as decorative objects for non-food items, just to be on the safe side. And if they are really unglazed, I’d also not use them as vases, because there will be moisture on all sides, including the bottom (speaking from experience, when I was younger and naïve).

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  • It's interesting that somehow these mugs manage to be susceptible to mold/bacteria from not being waterproof and at the same time threaten the risk of leaking heavy metals into food as indicated by the strong chemical smell.
    – PrashanD
    Sep 15, 2023 at 20:47
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    Double your pleasure! ;-)
    – FuzzyChef
    Sep 16, 2023 at 22:00

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