They should be safe unless they became unsealed. Sometimes water has a small bit of oil in it, without being dangerouse, and the oil/gas in the water will cause a black residue.

I also get black from tomato products. I think it is some chemical reaction between leaked tomato and the metal of the rings -- oxidized metal. It tastes metallic.
(I have not tasted it as an adult, but i remember from when I was a kid. Apparently I put everything into my mouth. I know what all kinds of stuff tastes like... playdoh, pencil erasers, wood and lead, dryrotted wood...)

I've gotten that too - usually with tomato products or pickles, especially when I use older rings that might be a little scratched or didn't get well scrubbed and dried completely before I put them away.

I just take some warm, soapy water on a cloth and wipe the threads well, rinse and dry.

Just another good reason to take the rings off before storage :-)

Rings are notorious for that for any acidic product. It's another argument in favor of removing rings after 24 hours, washing and drying thoroughly for future use.

Rings left on the jar over time can almost "glue" themselves to the threads.

Carol

Ditto here too, it's an oxidate and just wipe it off and it's safe. Almost glue? When I first started canning I left rings on, not knowing any better, and there were a few jars I NEVER got them off and were lost. Others, I had to rip the rings off with tools. Take them off for storage, please.

An automotive oil filter wrench works well on older wide mouth rings that were left on. Can't use the rings anymore, but they were likely shot anyway.

Pipe wrench works on regular rings.

Bought plenty of old jars with rusted on rings. Just have to be careful.

::Chuckling at the tool kit::

I know what you mean. I've used a strap wrench on rings and I've also discovered my spade-style ice cream scoop is perfect for releasing vacuum when my AA canner lid sticks. We all have our tool chests!

Carol