Hi, I have just purchased an Oigen tetsubin about two months ago, and during those time in use, appeared blue stain in the bottom of the pot. It happened suddenly at once. I don’t know what happened, and I’ve searched the internet for similar problems but couldn’t find any. Can anybody help me with this? I have attached a dropbox link below: thanks!
https://www.dropbox.com/sh/d4ryxwc7mnl ... j32Ea?dl=0