ASTM D6405-99(2014)

1.1 This practice covers extracting the tannin from raw and spent materials. The water extract obtained by this method is used to determine the tannin content of the original material. Analysis for total solids, soluble solids, and soluble non-tannins of the water extract from a material provides the information necessary to calculate the extractable tannin content of that material. The types of materials typically analyzed by this practice are products of plants such as woods, barks, leaves, nuts, fruits, roots, etc. and any of a wide variety of by-products (spent materials) from industrial processes utilizing plant products.