Some soaps contain pigs' fat or other animals not slaughtered Islamically. Furthermore, we do not know whether or not chemical change has taken place in the manufacturing process. Can such soaps be considered tahir? [Chemical change is a purifying agent in the sense that it purifies a najis item.]
Answer
If it is proven to contain those [impure] elements, it should be considered impure, except if the occurrence of chemical change is proven. Such a change is not proven in manufacturing of soaps.