本銀箔を硫黄で燻し、硫化反応により黒色に変化させた箔。銀は硫黄で燻すことで赤、青、黒へと変色します。銀箔を硫黄で燻す技術があるのは日本だけ。非常に限られた職人にしかできない技です。黒色まで変色すると箔自体がもろくなり、柔らかすぎて使いづらくなるため以前はあまり親しまれてきませんでしたが、技術の向上により2016年以降は実用できることがわかり、製品にも多く使われるようになりました。

It is a fumigated silver leaf with sulfur that discolor into BLACK by the sulfurization reaction. Silver is discolored into red, blue, and black by smoking in sulfur. The technique of smoking the silver leaf by sulfur is originally developed in Japan. It is a very special skill that can be done by limited craftsmen. Once discoloring into black, the leaf itself becomes very fragile and way too soft. That is why, it has not been used commonly. However, it was discovered to be adequate as practical use in 2016 and now is used in the many different products.