Gyokuhin 10.0-chō (Boku-Undo)

The ink color is a slightly cloudy reddish-brownish black. When used thick, it becomes a powerful black with a reddish tint.
This ink is suitable for Kanji practice and final drafts on Hanshi Paper or Gasenshi Paper. It can be used in a range of thicknesses from normal to thick.
The older it gets, the thicker it can be used. It seems unsuitable for light ink.

Kanji practice
Lamp-smoke ink
Ink color: Slightly cloudy reddish-brownish black / Dark ink: Strong black with a reddish tinge