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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?

user110084
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Seth
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2 Answers2

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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.

EDIT:

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.

tsturzl
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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. – rackandboneman Jun 06 '17 at 08:58
  • @rackandboneman Inclined to agree with you on that, adsorption risk if nothing else – user110084 Jun 06 '17 at 14:21
  • There is no chemical in an alkaline battery that would be corrosive to iron, in fact the battery housing is steel for exactly this reason. Being that it is steel to resist corrosion via outside sources such as water, and added durability. So it would not corrode iron, even if heated. – tsturzl Jun 06 '17 at 16:30
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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 Jun 06 '17 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 Jun 06 '17 at 16:39
  • @rackandboneman I would back that claim up with, say an MSDS. Because according to the MSDS provided in my answer you are wrong. – tsturzl Jun 06 '17 at 16:53
  • @tsturzl All the scales I have owned to date have CR type button batteries. Do these have non-rechargeable Li chemistry? Can't help wondering if a long hot citric bath after removing all the plastic might be the way to play safe. – user110084 Jun 06 '17 at 17:04
  • Mine takes 2 AAs. Those contain lithium in several toxic varieties that I would advise not touching whatsoever. – tsturzl Jun 06 '17 at 17:10
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    [CR button battery MSDS](https://www.buildingtechnologies.siemens.com/bt/global/en/bt-supplier-internet/spc/SPCDocs/Aboom%20CR%20batteries.pdf) – tsturzl Jun 06 '17 at 17:10
  • Wrong about what? About lithium contamination being a problem? Ah, I was unclear ... I was assuming there's stuff EVEN WORSE and especially more penetration capable than the lithium ... – rackandboneman Jun 06 '17 at 19:32
  • @rackandboneman That there are harmful additives in batteries, alkaline batteries contents are pretty straight forward, per the MSDS provided in my answer this is the same for all brands I could find. Lithium, mercury, and lead are the most harmful things contained in most batteries, none of these found in typical alkaline batteries. As far as lithium batteries lithium salt is incredibly dangerous, though none of these things will "penetrate" iron, hence why battery housings are hermetically sealed steal containers. – tsturzl Jun 07 '17 at 19:53
  • Furthermore these are no materials in NiHM, Lithium, or alkaline batteries that would corrode iron. The only battery that would do this would be one typically found in your car(lead acid battery). Even then, KOH isn't toxic in its own, but its very caustic. In fact KOH, as previously state is often used to clean cast iron because it will not effect the metal. – tsturzl Jun 07 '17 at 19:56
  • KOH along with zinc or magnesium oxide form the electrolytes in just about all common house hold batteries. Still haven't found these mystery additives that you speak of on any MSDS. It would be illegal to not list any substances that are toxic, corrosive, caustic, irritants, or otherwise questionable in terms of safety and cleanup of the material. Please back your statements with facts, not suspicions. – tsturzl Jun 07 '17 at 19:59
  • @tsturzl yes, but are batteries as supplied along inexpensive scales usually by the brands that will even publish a datasheet? I'd be wary of a situation like it is with cheap CFLs - even if the design is made to work with a very minimal amount of mercury, someone in the manufacturing chain might think putting in excess mercury is cheaper than measuring it precisely... – rackandboneman Jun 07 '17 at 22:12
  • Batteries are required to supply a datasheet in the united states in order to be sold. – tsturzl Jul 31 '17 at 23:16
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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.

Sally
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  • DO NOT do this if you're batteries contain mercury, lithium, or acids. This could create very harmful vapors. – tsturzl Jun 07 '17 at 19:51