If a proprietor uses a denaturant that is difficult to dissolve in spirits at normal working temperatures, that is highly volatile, or that becomes solid at normal working temperature, the proprietor may liquefy or dissolve the denaturant in a small amount of spirits or water prior to its use in the production of denatured spirits. However, the proof of the denatured spirits produced must not fall below the proof required by the approved formula. In addition, if alcohol is used as a solvent, the proprietor must include this additional alcohol in calculating the total quantity of spirits denatured in the batch.

(26 U.S.C. 5242)