Mysterious Inky Copper Color Metal In Bottom Of Tetsubin

[Paintedfoxglove]

I was wondering if anyone has seen anything like these raised copper color pieces in their tetsubin. They have an almost inky black base with a copper sheen and they’re surrounded by what looks almost like an oil stain. There are also little clear shimmery parts (something akin to clear nail polish).

This tetsubin was purchased as a vintage piece and I am not aware of it’s history of use (as in, I’m not sure if it was ever used in a way that it was not intended to be used).

I didn’t know if this was the result of common misuse or indicative of it being used for melting other metals / materials.

Any information or insight is greatly appreciated.

-Alisha

[Paintedfoxglove]

Update:

I have recently found that these spots are consistent with regular wear and maybe some lack of care. It did test negative for lead.

A great place for research is Oitomi Foundry’s YouTube channel, specifically video Vol. 6. It’s in Japanese, but you can see clear examples of the same textures. It is said it can be remedied by boiling green tea packets for 30 minutes in a cup full of water (more added if it gets low), turn off the heat and let stand around 8 hours. The liquid and spots should turn black from reacting with the tannins in the tea. Repeat as needed. Then boil with clear water and use as normal.

I hope this is helpful to someone and I would just like to say I really appreciate all of the useful information on this tea forum. Thanks!