What Is Alcohol Denat. Sd Alcohol 39-A?
Alcohol Denat. Sd Alcohol 39-A is a form of ethyl alcohol that has been “denatured,” meaning it contains small amounts of t-butyl alcohol plus either quinine, quinine bisulfate, quinine dihydrochloride, cinchonidine or cinchonidine sulfate. These added substances make the alcohol unfit for drinking yet leave its performance in cosmetics unchanged. The base ethanol is usually produced by fermenting plant sugars from sources like corn, beets or sugarcane, then distilled to high purity. During denaturing, precise amounts of the listed agents are blended in accordance with United States regulations (27 CFR 21) to ensure the finished liquid cannot be consumed.
Ethyl alcohol has been used in personal care since the early days of perfumery because it evaporates quickly and can dissolve both fragrance oils and certain skincare actives. As governments sought to discourage misuse, specialized denatured grades like SD 39-A were introduced so manufacturers could buy alcohol at a lower tax rate while meeting safety standards. Today this ingredient shows up in a wide range of beauty products, especially where a fast-drying, clean feel is desired. You’ll commonly find it in facial toners, fragrance mists, hair sprays, makeup setting sprays, hand sanitizers, light lotions, gels and some peel-off masks.
Alcohol Denat. Sd Alcohol 39-A’s Cosmetic Benefits/Uses
In formulations SD Alcohol 39-A serves one key purpose: it is a solvent that dissolves oils, resins and other active ingredients then flashes off the skin or hair in seconds. This rapid evaporation creates a weightless finish, helps fragrances disperse evenly and speeds up the drying time of sprays, gels and lotions. Its solvent power also keeps formulas clear and stable, allowing chemists to achieve elegant textures without heavy emulsifiers.
Who Can Use Alcohol Denat. Sd Alcohol 39-A
Because SD Alcohol 39-A evaporates almost instantly it suits normal, combination and oily skin that enjoys a light dry finish. Dry or very sensitive complexions may find frequent use leaves them feeling tight since the rapid evaporation can pull water from the surface. If you fall into that category look for formulas where the alcohol is balanced by humectants or emollients.
The ingredient is plant derived and contains no animal by-products so it is suitable for vegans and vegetarians.
No specific restrictions exist regarding pregnancy or breastfeeding, yet out of caution anyone who is pregnant or nursing should run products containing SD Alcohol 39-A by a qualified healthcare professional first as this is not medical advice.
SD Alcohol 39-A does not increase photosensitivity so it will not make skin more prone to sunburn. As with all volatile alcohols keep it away from open cuts or the eye area where stinging can occur.
Potential Side Effects/Adverse Reactions
Reactions to topical SD Alcohol 39-A differ from person to person. The points below cover potential side effects yet most users will not experience them when the ingredient is formulated and used correctly.
- Dryness or tightness High evaporation can remove surface moisture leaving skin or hair feeling parched
- Irritation or stinging Especially on compromised skin barriers freshly shaved areas or around the eyes
- Redness or flushing Short lived vascular response in those with rosacea or highly reactive skin
- Contact dermatitis Rare allergic response to the denaturants rather than the ethanol itself
- Excessive hair dryness In styling sprays overuse may leave strands brittle and dull
If any adverse effect crops up discontinue use immediately and consult a healthcare professional.
Comedogenic Rating
Rating: 0/5
SD Alcohol 39-A is a lightweight volatile liquid that evaporates almost as soon as it is applied so it leaves no oily or waxy residue that could block pores. Because it does not linger on the skin or mix with sebum its chance of triggering comedones is considered extremely low.
This makes the ingredient generally suitable for acne-prone or breakout-prone skin, provided the rest of the formula is also low in pore-clogging agents.
On very dry or compromised skin the temporary dehydration it can cause might prompt compensatory oil production, which indirectly could contribute to congestion, but this is a formulation-dependent issue rather than a property of the alcohol itself.
Summary
Alcohol Denat. SD Alcohol 39-A is used mainly as a fast-evaporating solvent that dissolves fragrance oils actives and film-formers then flashes off to leave a weightless, quick-dry finish. Its high volatility helps products feel lighter and aids even dispersion of ingredients, while also acting as a short-term antimicrobial carrier in items like hand sanitizers.
Thanks to its effectiveness and relatively low cost it remains a staple in perfumes, setting sprays, toners, sanitizers and styling products, though some brands targeting sensitive or ultra-hydrating niches avoid it in favor of gentler solvents.
The ingredient is considered safe for topical use within normal cosmetic concentrations, yet anyone new to a product should still perform a small patch test first to rule out individual sensitivity.