I am a baker and just moved houses. I used my cast iron to hold my electronic scale, which is made of plastic and had batteries in it, and without checking put the whole container into the oven at 450. I realized my mistake not soon enough, and while the plastic was not molten, the batteries had certainly exploded by the time I took everything out. Uh oh.

How could I clean battery acid/plastic off my cast iron to make sure its safe to eat from?

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    If these were off brand batteries, treat any residue as if it contained mercury. Commented Jun 6, 2017 at 8:53

2 Answers 2


Lots of of abrasives. Electrolytes from the batteries won't soak into the iron, and lithium is not soluble in solid iron if they happened to be lithium batteries. If you can get all the plastic completely removed, the chemicals from the battery are water soluble so it will just wash off.


Depending on your battery type, you might want to dispose of the pan. If alkaline batteries were used, be aware that the electrolytes from the battery are caustic. They can cause tissue damage(topical burns), which should be treated with soap and water.

Either way, cleaning the pan could be dangerous, and you might consider throwing it out completely, because of the precautions you'd need to take. However the pan should not have suffered any corrosion from the battery, metal is non reactive with a base, and there is no compound in a alkaline battery that is reactive with metals. You can confirm this via the MSDS for most batteries. KOH is the only chemical that is corrosive, but its not corrosive to iron. In fact KOH is commonly used to clean cast iron, because it will corrode everything but the iron.

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    Lithium wouldn't be the issue here - and there are a lot of different electrolytes and additives around, some corrosive enough to create their own kind of porosity - I wouldn't trust a cast iron surface that had that kind of stuff on it unless I could polish it down to smooth, bare metal. Commented Jun 6, 2017 at 8:58
  • @rackandboneman Inclined to agree with you on that, adsorption risk if nothing else
    – user110084
    Commented Jun 6, 2017 at 14:21
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    Unless you had a lead acid battery in there, but I've never heard of anyone putting a car battery in a kitchen scale. But that's just me
    – tsturzl
    Commented Jun 6, 2017 at 16:33
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    Further more these consumer batteries(alkaline) were create specifically with the purpose of being able to dispose of the electrolytes without special treatment. Lithium and rechargable batteries would be an issue, and likely not with corrosion, but heating either of those can be problematic because mercury vapor is the leading cause of mercury poisoning and both those battery types contain mercury and other dangerous metals(lithium, lead, cadmium). So lithium and other toxic metals would 100% be the concern here, unless the batteries are rechargable lithium, or lead acid. Both unlikely.
    – tsturzl
    Commented Jun 6, 2017 at 16:39
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    CR button battery MSDS
    – tsturzl
    Commented Jun 6, 2017 at 17:10

I would run it through a long cycle in a self-cleaning oven. This will take it down to the bare metal. (If it doesn't, do it again.). You will, of course, have to completely re-season your pan from scratch.

  • DO NOT do this if you're batteries contain mercury, lithium, or acids. This could create very harmful vapors.
    – tsturzl
    Commented Jun 7, 2017 at 19:51

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