(a) Olive, palm-kernel, rapeseed, sunflower, and sesame oil shall be classifiable under subheadings 1509.10.20, 1509.10.40, 1509.90.20, 1509.90.40, 1510.00.20, 1512.19.20, 1513.29.00, 1514.90.10, 1514.90.50, 1515.50.00, Harmonized Tariff Schedule of the United States, if denatured abroad or under Customs supervision after importation but before release from Customs custody, at the request and expense of the importer, by a formula prescribed by Headquarters, U.S. Customs Service, or if by their method of production abroad they are rendered unfit for use as food or for any but mechanical or manufacturing purposes.

(b) Each cask or package of oil claimed to have been before importation denatured or otherwise rendered unfit for use as food or for any but mechanical or manufacturing purposes shall be sampled and tested by an appraising officer.

(c) Formulas prescribed by Headquarters, U.S. Customs Service, except proprietary mixtures, will be circulated to all Customs officers and will appear as abstracts of United States Customs Service decisions published in the weekly Customs Bulletins. Proprietary mixtures approved by the Commissioner of Customs will not be published but appropriate notice of their approval will be given to all Customs officers.

(d) The Headquarters, U.S. Customs Service, will from time to time prescribe additional formulas, and will consider any formula for special denaturing that may be submitted.

(e) The Center director may, if he deems it advisable, require an importer requesting permission to use any authorized denaturant to submit to the appraiser an adequate sample of such denaturant, in order that the appraiser may report to the Center director whether or not such denaturant is suitable for rendering the oil unfit for use as food or for any but mechanical or manufacturing purposes.

(f) No such oil shall be released free of duty until the appraiser shall have made a special report that it has been properly denatured.