Wash. Rev. Code § 66.12.130
Nothing in this title shall apply to or prevent the sale, importation, purchase, production, or blending of alcohol used solely for fuel to be used in motor vehicles, farm implements, and machines or implements of husbandry or in combination with gasoline or other petroleum products for use as such fuel. Manufacturers and distillers of such alcohol fuel are not required to obtain a license under this title. Alcohol which is produced for use as fuel shall be denatured in accordance with a formula approved by the federal bureau of alcohol, tobacco and firearms prior to the removal of the alcohol from the premises as described in the approved federal permit application: PROVIDED, That alcohol which is being transferred between plants involved in the distillation or manufacture of alcohol fuel need not be denatured if it is transferred in accordance with federal bureau of alcohol, tobacco and firearms regulation 27 C.F.R. 19.996 as existing on July 26, 1981. The exemptions from the state liquor control laws provided by this section only apply to distillers and manufacturers of alcohol to be used solely for fuel as long as the manufacturers and distillers are the holders of an appropriate permit issued under federal law.
RCW 66.12.130