yellow or light brown light without crystal powder ; odourless, has a special odor, very acerbity. soluble in water and ethanol, soluble in glycerin, hardly soluble in ether, chloroform and benzene. its aqueous solution and ferric salt solution meet blue-black, add sodium sulfite can delay the discoloration. in industry, tannic acid is widely used in tanning and manufacturing blue ink. tannic acid can make protein coagulation. people put the pig skin, cowhide chemical treatment with tannic acid, can make the rawhide soluble protein in the set. so, had put a few days will smells rotten raw hides, turned into a beautiful, clean, flexible, durable leather. this kind of leather making process, called leather tanning
appearance light yellow or pass
light brown powder
solid content(%) ≧ 81.0 81.50
drying loss(%) ≦ 9.0 8.0
insoluble (%) ≦ 0.6 0.20
color ≦ 2.0 1.3