# 19.348 Formula requirements.A proprietor must obtain approval of a formula on form TTB F 5100.51 as provided in §§ 5.192 and 5.193 of this chapter before a proprietor may:(a) Blend, mix, purify, refine, compound, or treat spirits in any manner which results in a change of character, composition, class, or type of the spirits, including redistillation as provided in § 19.314; or(b) Produce gin or vodka by other than original and continuous distillation.(26 U.S.C. 5201, 5555)[T.D. TTB-92, 76 FR 9090, Feb. 16, 2011, as amended by T.D. 196, 89 FR 87939, Nov. 6, 2024]