27 CFR §20.215

1. (a)The proprietor of a distilled spirits plant authorized to produce distilled spirits may receive for redistillation (1) articles manufactured under this part which contain denatured spirits, and (2) spirits residues of manufacturing processes related to the manufacture of these articles.
2. (b)Any person shipping these articles or spirits residues to a distilled spirits plant for redistillation shall—
   1. (1)Identify each package or articles or spirits residues as to contents, and
   2. (2)Mark and serially number each package as provided in § 20.214.