Sometimes my flatware leaves grey streaks in butter. I've only seen this with knives in cold butter. They claim to be stainless steel which I would think wouldn't do this. If I recall they were the very best flatware Target had to offer ;) Is something leaching into my food?

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  • 9
    Clean your knife.
    – Batman
    Commented Nov 30, 2014 at 17:10
  • 2
    Might this be a knife shaped object made of aluminium, that has been bin the dishwasher? Commented Mar 1, 2018 at 20:38
  • It could be (black) rust. Which means you put it in the dishwasher way too dirty. Or it sat dirty in the sink for a month...
    – Mazura
    Commented Dec 28, 2018 at 0:22

1 Answer 1


The photo suggests you are using a knife that has serrations. Dirt can get trapped between the serrations. This is not likely to be metal from the knife, but the dirt.

  • 4
    I'd wager its a bit of char from a piece of toast, jammed up in the serration.
    – Preston
    Commented Dec 1, 2014 at 1:41

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