Oak gall مازو

Oak galls (مازو, mazu) are hard growths on oak buds and leaves caused by gall wasps. They are very rich in tannin, and tannin with iron gives black, the chemistry of iron-gall ink. Iranica records oak galls as a source of black for rug wool in parts of Iran. Blacks and browns made with tannin and iron weaken wool, and they are the colours that corrode.

Also gallnut · mazu · tannin black · iron black

See also Mordant, Corrosion, Walnut husk

Last reviewed November 2026