What is meant by the complete transformation (Istihalah Tammah) of alcohol during manufacturing?

Impurities are purified by transformation (istihalah); this is the change of one substance into another that differs from it in definition and reality. So, if alcohol, which is impure, transforms into another substance and its original characteristics disappear, then it becomes pure. It is permissible to use creams to which it has been added after its transformation. However, if alcohol is added before its transformation, the creams become impure, and it is not permissible to use them. As for one who is in doubt, he should avoid doubtful matters.