Denatured ethanol is ethyl alcohol (ethanol) that has been blended with additives called denaturants to make it unfit for drinking. Because denatured ethanol cannot legally be consumed as a beverage, it is exempt from the federal excise tax of $13.50 per proof gallon that applies to distilled spirits. The Alcohol and Tobacco Tax and Trade Bureau (TTB) recognizes two categories: Specially Denatured Alcohol (SDA), which requires a TTB permit to purchase and use, and Completely Denatured Alcohol (CDA), which most buyers can purchase without a permit. Every approved formula — the exact denaturant and the amount added per 100 gallons of ethanol — is published in 27 CFR Part 21.
Why Ethanol Is Denatured
Pure ethyl alcohol is chemically identical whether it ends up in a bottle of spirits or a batch of hand sanitizer. Federal law taxes beverage alcohol at $13.50 per proof gallon, which would roughly double or triple the cost of ethanol for industrial buyers. Denaturing solves this: by adding small amounts of unpalatable or toxic compounds, the alcohol is rendered undrinkable, and the excise tax no longer applies. The denaturants are chosen so the ethanol still performs its job as a solvent, extraction medium, or ingredient carrier — it just can never be sold or consumed as a beverage.
SDA vs CDA: The Two Categories of Denatured Ethanol
The practical difference between the two categories comes down to how aggressive the denaturants are and what paperwork is required to buy the product.
| Category | TTB Permit Required? | Typical Denaturants | Common Uses |
|---|---|---|---|
| SDA (Specially Denatured Alcohol) | Yes — industrial alcohol user permit | Small additions matched to end use (methanol, isopropyl alcohol, tert-butyl alcohol, denatonium benzoate) | Cosmetics, fragrance, pharmaceuticals, lab reagents, extraction |
| CDA (Completely Denatured Alcohol) | No permit for most end uses | Heavier additions such as toluene or heptane | Fuel, cleaning, coatings, general industrial solvent work |
SDA formulas use the mildest denaturing that still satisfies the TTB, which keeps the ethanol suitable for sensitive applications like skin-contact products. The tradeoff is oversight: SDA buyers must hold a TTB industrial alcohol user permit under 27 CFR Part 20. CDA formulas are denatured thoroughly enough that the TTB does not require a permit for most purchasers.
Common SDA Formulas and What They Are Used For
SDA 3-A
SDA 3-A adds 5 gallons of methanol per 100 gallons of ethyl alcohol. It is a workhorse formula for industrial processes, coatings, and chemical manufacturing where a simple, well-understood denaturant is acceptable. See our SDA 3-A denatured ethanol page for available proofs and packaging.
SDA 3-C
SDA 3-C adds 5 gallons of isopropyl alcohol per 100 gallons of ethanol. Because the denaturant is IPA rather than methanol, 3-C is often preferred where methanol is undesirable in the process or the residue profile. Details are on our SDA 3-C denatured ethanol page.
SDA 40-B
SDA 40-B is denatured with tert-butyl alcohol and denatonium benzoate (Bitrex), one of the bitterest substances known. Because the denaturant load is tiny and nearly odorless, 40-B is the formula of choice for perfumes, colognes, hair sprays, and other personal care products. Our SDA 40-B denatured ethanol is available in 190 and 200 proof.
Reagent Alcohol
Reagent alcohol is a lab-standard blend of roughly 90% ethanol, 5% methanol, and 5% isopropyl alcohol. It behaves like pure ethanol in most laboratory procedures while remaining exempt from beverage taxation. See our reagent alcohol page.
CDA 12-A: The Permit-Free Option
CDA 12-A adds 5 gallons of toluene or 5 gallons of heptane per 100 gallons of ethanol, per 27 CFR 21.26. Because it is completely denatured, most buyers can purchase CDA 12-A without any TTB permit, making it the fastest route to high-purity ethyl alcohol for cleaning, fuel, and general solvent applications.
How to Choose the Right Denatured Ethanol
Start with your end use, then work backward to the mildest formula that satisfies it. Fragrance and personal care formulators almost always land on SDA 40-B. Labs typically specify reagent alcohol. General industrial users who want to skip permitting choose CDA 12-A. If your process cannot tolerate any denaturant, non-denatured 190 proof or 200 proof ethanol is the answer — keeping in mind that 200 proof material is specified at under 0.5% water and that non-denatured alcohol carries its own TTB requirements. For a breakdown of how the two proofs differ, read our guide on 190 proof vs 200 proof ethanol.
Pristine Alcohol distills every gallon from 100% Michigan corn in 100% stainless steel equipment at our facility in Marysville, Michigan, so the same purity standards apply whether you order denatured or non-denatured ethyl alcohol.
Frequently Asked Questions
Is denatured ethanol the same as denatured alcohol?
Yes. “Denatured alcohol” almost always refers to denatured ethyl alcohol. The terms are used interchangeably in industry and in TTB regulations.
Do I need a TTB permit to buy denatured ethanol?
It depends on the category. SDA formulas such as 3-A, 3-C, and 40-B require a TTB industrial alcohol user permit. CDA formulas such as 12-A can be purchased by most buyers without a permit.
Can denatured ethanol be made drinkable again?
No. Removing denaturants is both impractical and illegal. Denaturant systems are designed to resist separation, and attempting to recover beverage alcohol from denatured ethanol violates federal law.
What proof is denatured ethanol?
Denatured formulas are built on a high-proof ethanol base, most commonly 190 proof (about 95% ethanol) or 200 proof, which is specified at under 0.5% water.
Which denatured ethanol is best for cosmetics and fragrance?
SDA 40-B. Its denaturants — tert-butyl alcohol and denatonium benzoate — are used in such small quantities that they do not interfere with fragrance profiles or skin-contact formulations.
Need bulk denatured or non-denatured ethyl alcohol? Request a quote or contact Pristine Alcohol for pricing on drums, totes, and tankers.