This International Standard specifies a method for determining the solubility of wool in alkali. The method is applicable to wool textiles in any form, namely loose fibre, sliver, roving, yarn or cloth. The test is most useful when an untreated control sample is available and when the nature of the treatment of the sample under test is known, i.e. as a method of control. When the sample has been treated by two agencies having opposite effects on the solubility, the interpretation of the results, even when an untreated control sample is available, is difficult and may be misleading.