27 CFR §19.384

1. (a)When making denatured spirits, a proprietor must mix the denaturants and spirits only in packages, tanks or bulk conveyances and only on bonded premises. A proprietor must thoroughly mix the denaturants with the spirits to ensure that all of the spirits are effectively denatured.
2. (b)If a proprietor wishes to use another method of mixing denaturants and spirits not prescribed in this subpart, the proprietor must submit to the appropriate TTB officer a written application for approval of the alternative method in accordance with § 19.27. TTB may require that the proprietor submit additional information, including a flow diagram or other graphic representation of the alternative method, in support of the application.