Staff Answer
May 29, 2026 - 02:19 PM
SDA stands for Specially Denatured Alcohol. The "40B" is the federal formula designation under 27 CFR § 21.76, which specifies exactly which denaturants are added: tert-butyl alcohol and denatonium benzoate. Denaturing renders the ethanol undrinkable, which exempts it from federal beverage excise tax (~$27/gal) and drops the cost significantly while keeping it usable for any non-ingestible application.
