This International Standard specifies a method for determining the dichloromethane-soluble matter in combed wool sliver. Its use can be extended to wool in other forms. It should be recognized that extraction with dichloromethane under the prescribed conditions does not completely remove all the fatty material present in a sample of wool. A further amount, possibly material of similar character, will usually be extracted by the use of solvents that cause greater swelling of the wool fibres. The method is applicable only to 100 % wool products. It can give misleading results if applied to products in which fibres other than wool are present.