Tannic Acid Powder

Tannic acid (tannin, C₇₆H₅₂O₄₆) is a plant-derived polyphenol supplied as a fine light yellow to pale tan powder, rich in gallotannins. It dissolves in both water and alcohol systems and works as an astringent, a metal-complexing agent and mordant, and an antioxidant.

It is used as a dye fixative and mordant in natural dyeing, as the vegetable tannin in leather tanning, and in iron-based alternative photographic processes such as Van Dyke brown, kallitype and argyrotype. Woodworkers use it to raise tannin content for iron-acetate staining and antiquing, and it appears as an organic fuel in smoke and colored-flame pyrotechnic compositions.