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Based on an article I found online about how to disinfect hygiene tools I've been soaking nail clippers and similar items in a mixture of white vinegar, dish soap, and warm water for a few hours in a plastic sandwich container.

So far it's been fine, but recently did it with a stainless steel cuticle nipper and after taking it out and rinsing it and drying it off, the metal had turned a dark gray color it's giving off a foul odor.

What happened to the metal, and is the tool still safe to use?

For reference, here is a photo of the tool (on top) and a different one showing what it used to look like (bottom).

enter image description here

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  • $\begingroup$ From what material was the container holding the solution made? $\endgroup$ – Agriculturist Nov 6 '18 at 1:44
  • $\begingroup$ Updated to reflect that it was a plastic sandwich container. Side note: I only use the container for this and will never use it for food storage. $\endgroup$ – Employee Nov 6 '18 at 15:30
  • $\begingroup$ A plastic container rules out a galvanic reaction with the container. It looks like the acid in the solution dissolved the stainless steel coating. Not all coatings or stainless steel is the same so it is hard to say exactly what happened. If the tool smells bad then get rid of it. Bad smells are one way our body warns us that something is not safe Homebrew solutions involving mixing cleaners is risky. Scalding hot water (or steam) is a much safer way to disinfect tools because it will not leave a harmful residue. $\endgroup$ – Agriculturist Nov 6 '18 at 16:15
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What grade of stainless steel was the clipper made of? Was it labeled stainless steel, or is this an assumption because it looked shiny or similar to some other corrosion-resistant object (which may itself be stainless steel or not)?

Test with a magnet: if they are non-magnetic, the clippers could be stainless steel. Without knowing more about the source of the clippers, I could guarantee you that they are not stainless steel - after, they were not stain-less even in vinegar.

It is difficult to imagine any kind of heat treatment or surface treatment (short of plating with a more active metal) that could result in this kind of generalized corrosion.

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  • $\begingroup$ (+1) Good answer. I would bet the clippers are an aluminum or zinc alloy, maybe plated with nickel. If they are really stainless steel, they are awful. $\endgroup$ – Ed V May 4 at 17:43
  • $\begingroup$ This answer covered it very well . I could add that martensitic and ferritic stainless steels are magnetic , but these stainlesses would not be darkened or otherwise affected by your cleaning. Possibly there is some deposit from the cleaning solution. Another guess is German Silver, actually a brass made silver color by addition of several per-cent nickel , But I don't even like that guess. $\endgroup$ – blacksmith37 May 5 at 0:49

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