Explanatory notes
… The heading covers tannins (pyrogallol and catechol tannins) whether or not containing impurities from … oak bark tannin (quercitannic acid), chestnut wood tannin (castaneotannic acid), quebracho tannin, mimosa tannin, etc. … in this heading include those of aluminium, bismuth, calcium, iron, manganese, zinc, hexamethylenetetramine, …