Red Stamping Ink, Inju(in meaning 'seal', ju meaning 'red')

Reddish material used for stamps. Made with castor oil and cinnabar on a cotton-like material.
Synonyms include seal ink, seal clay, ink paste, and chop ink.

Reddish colorant used when impressing seals or stamps. Used for centuries with the development of seals in China, and currently still being used widely throughout Asia. Premium Iines use mercury and cadmium red as ingredients, while the general-use includes lake color into the mix.

The main ingredint for the seal ink, mercuric sulfide, is a mercury compound that is scarlet red in color. In addition, the color of the castor oil is also red and is a type of non-drying oil. Ink paste suitable for stamps or seals were made by utilzing the characteristics of the ingredients that do not react to air, come off easily on paper due to high viscosity, less prone to change under heat and quick-drying with a low solidifying point.