There are no postal requirements to denature the contents (i.e., to change the nature or natural qualities) of intoxicating liquor. However, if contents are denatured through the use of such elements as sodium bisulfate (a corrosive) or mercuric chloride (a poison), the substances must meet the mailability requirements in chapter 3 for a Class 8 corrosive material or a Division 6.1 toxic substance, as appropriate. If the contents are flammable or combustible, the material must meet the requirements for a Class 3 flammable or combustible liquid in chapter 3.
