Gallnut is the earliest and richest source for natural colourless tannin and is found in the gallnuts of oak trees. They are produced by insects who deposit their eggs in small punctures they make on young branches. The tree excretes a tannin rich substance that hardens to form a gallnut. These are collected and ground for use as a tannin mordant for cellulose fibres, in the leather tanning industry, and for medicine. This extract is a rich source of gallic acid. Mordant using 6%-8% WOF
Tannin is used as part of the mordant process for cellulose fibres and fabrics. Alum does not bond as well with cellulose fibres as it does with protein fibres. Tannin bonds well with cellulose. and once treated with tannin, alum will combine with the tannin-fibre complex. Many dyestuffs contain tannin (black oak, pomegranate, quebracho, fustic, etc) and do not need an additional tannin. The two most popular tannins in the Maiwa studio are oak gall and myrobalan.
Tannins can be clear or they can add colour to the fibre, and this is an important consideration when selecting a tannin.
• Clear Tannins: “Gallic” - Gallnut, Tara, some Sumacs
• Yellow Tannins: “Ellegic” – Myrobalan, Pomegranate,
• Red-Brown Tannins: “Catechic” – Cutch, Quebracho, Tea leaves, and some Sumacs.