19 CFR 10.304 - Exclusions.
(a)Changes based on simple processing. No goods shall be considered originating for purposes of eligibility under the Agreement if they have merely undergone simple packaging or simple combining operations, or have undergone mere dilution with water or with another substance that does not materially alter the characteristics of the goods.
(b)Other excluded processing. No goods shall be considered to be originating merely by virtue of having undergone any process or work in which the facts clearly justify the presumption that the sole object was to circumvent the provisions of Chapter 3 of the Agreement.