1.1 This standard specifies methods for determining free sulfur in vulcanized rubber. There are four types of this method. Namely, there are two types of copper mesh method (method A and method B), sodium sulfite method and bromine method. 1.2 The copper mesh method can also be applied to unvulcanized rubber, subject to the restrictions in paragraph 4. Annex A shows the influence of sulfur in various vulcanization accelerators on the free sulfur determination method.