I've opened a new tin of gin and tonic from samuel gawith and noticed a weird "ring" of darker snuff surrounding the edge of the tin. It's certainly not rust - tin looks brand new after removing darker snuff from the edges. It seems like it's just much more moist. Could that be a first sign of mildewing? I've asked the same question on a facebook group and someone said that this could be caused by condensation, which seems reasonable.
Snuff darkens as it gets moist, if the snuff is noticably more moist around the edges then the edges will be darker. When snuff goes moldy you will visually see whitish fuzz growing on and in the snuff.
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