Hello,
I have a Kunzan workshop made tetsubin that I have been using for about two years now. I recently discovered that there is a black soot like residue that will come off if you touch the inside of the kettle. This is particularly near the urushi lacquer spots and will leave a very black smudge if you touch it. The water coming from the pot has been fine and I have not noticed any issues there.
Does anyone know if this can be repaired easily or if it's something that would need professional attention?
Thanks!
Testsubin Black Residue
This is a bit strange. Have you done the tea treatment recently? It looks kind of like a blackened rust iron residue. Normally i'd expect such residues to wash out gradually as you boil water in it, although that might depend on your water. It doesn't look like something to worry about as long as it is not affecting the taste of the water. Gentle cleaning with water and a towel should not hurt though.
If you are heating it over gas, I suppose there is the possibility that incomplete combustion could leave soot. I cant quite tell from what part of the tetsubin you are finding this soot-like substance but I have seen actual soot from gas stoves find its way quite far up the outside of kettles.