AS 1301.004:2019 PDF
This Standard sets out a method to be used to determine the proportion of material in wood which is soluble in boiling water.
This determination is a measure of the materials in wood (or pulp) which are soluble in boiling water. They may include tannins, kinos, colouring matter, sugars, free acids and free mineral matter. The values obtained are arbitrary because departures from the conditions laid down can cause more or less material to be extracted. Since hot water has a limited hydrolytic effect on wood, which increases with time of extraction, some water soluble hydrolysis products are extracted along with the soluble material initially present.