One gallon of 100 percent acetaldehyde or 5 gallons of an alcohol solution of acetaldehyde containing not less than 20 percent acetaldehyde, or 1 gallon of ethyl acetate having an ester content of 100 percent, or, where approved by the appropriate TTB officer, as to material and quantity, not less than 6.8 pounds if solid, or 1 gallon if liquid, of any chemical. When material other than acetaldehyde or ethyl acetate is proposed to be used, the user shall submit an application for such use to the appropriate TTB officer. The application shall include specifications, assay methods, and an 8-ounce sample of the substitute material for analysis.
27 C.F.R. § 21.56