Tannin (tannic acid)
Very light brown, to brown highlights, to color changer. Used in the mordant process for cotton.
Dissolve in cold water, then add boiling water to dissolve. Strain into dyepot. Add wet, mordanted fiber and simmer 1 hour. Use 3-10 % WOG
Tannin is found in several dyes, occurring naturally. Dyes such as walnut, chestnut, myrobalan and wattle are fairly high. Others, especially the Quebracho family of dyes, contain moderate amounts. Because of this tannin content, some dyes are also used as mordants and some may also assist as surface design tools. Tannin, like iron, has numerous surface design uses acting as a resist or discharge agent.
The use of tannin in mordanting cellulose can be found in the potassium alum sulfate section