Description Oak timber contains tannin, which reacts with iron to make a black colour. This was the basis for the manufacture of black ink. When turning unseasoned oak, I have to protect it from contact with iron or steel to prevent staining. But in this case, I immersed the bowl in a solution of iron overnight. It developed a deep, permanent black colour. This small bowl was made from the wood of a big old oak tree that fell in a gale. It has a small natural fissure. Related
