What Is Sd Alcohol 39-A?
Sd Alcohol 39-A is a form of denatured ethyl alcohol produced by fermenting plant sugars, most commonly from corn. Once the ethanol is distilled it is “denatured,” meaning tiny amounts of bitter or unpalatable agents such as tert-butyl alcohol and denatonium benzoate are added so the liquid cannot be consumed. This step allows the ingredient to be used in cosmetics without the taxes or regulations that apply to drinkable alcohol.
The cosmetic world has leaned on denatured alcohol for decades because it is affordable, dries fast and blends well with both water and oil. Sd Alcohol 39-A in particular gained popularity in mid-20th-century skin tonics and colognes that aimed for a crisp clean feel. Modern formulators still turn to it when they want a weightless finish or need to dissolve ingredients that water alone cannot handle.
Production starts with the fermentation of corn or other grains to create ethanol. The liquid is then distilled to raise purity, after which the chosen denaturants are mixed in. The final step is filtration and quality checks before shipment to cosmetic manufacturers.
You will most often see Sd Alcohol 39-A in facial toners, makeup setting sprays, hair sprays, aftershaves, quick-dry nail products, lightweight lotions and gel-type moisturizers where a non-greasy feel is key.
Sd Alcohol 39-A’s Cosmetic Benefits/Uses
In formulas Sd Alcohol 39-A serves several jobs that boost product performance
- Astringent: Helps tighten the look of pores and gives skin or scalp a fresher matte finish which is why it is common in toners and oil-control sprays
- Solvent: Efficiently dissolves fragrances, plant extracts, resins and film-formers so the finished product is clear and evenly mixed
- Viscosity controlling: Thins out heavy formulas making them feel light and quick to absorb while also helping sprays mist more evenly
Who Can Use Sd Alcohol 39-A
Most people with normal, combination or oily skin can use products that contain Sd Alcohol 39-A without issue because it evaporates quickly and leaves little residue. Dry or sensitive skin types may find it too stripping since rapid evaporation can pull moisture from the surface, sometimes leading to tightness or flaking. Those with existing skin barrier concerns such as eczema or rosacea should approach with caution for the same reason.
Sd Alcohol 39-A is plant-derived and contains no animal by-products so it is suitable for vegans and vegetarians. The denaturants added are also synthetic or plant based rather than animal sourced.
No specific warnings link Sd Alcohol 39-A to pregnancy or breastfeeding complications. That said this is not medical advice and anyone expecting or nursing should review any product that includes denatured alcohol with a healthcare professional before regular use.
The ingredient does not make skin more sensitive to sunlight so there is no increased risk of sunburn or hyperpigmentation from its presence in a formula.
Potential Side Effects/Adverse Reactions
Responses to topical Sd Alcohol 39-A differ from person to person. The points below outline potential effects though most users will not experience them when the ingredient is used at standard cosmetic levels.
- Dryness or dehydration
- Sensation of tightness or stinging on sensitive areas
- Temporary redness or irritation in those with a compromised skin barrier
- Flaking or rough texture after repeated heavy use on already dry skin
- Eye irritation if sprayed too close to the eyes
If any of these reactions occur discontinue use and consult a healthcare professional if symptoms persist or worsen.
Comedogenic Rating
Rating: 0
Sd Alcohol 39-A is highly volatile and evaporates within seconds so it does not linger on the skin long enough to mix with sebum or block pores. Because it leaves no occlusive film researchers and dermatology references classify it as non-comedogenic. It is therefore generally suitable for people who are prone to acne or breakouts. Very dry or compromised skin may still react with irritation which can indirectly aggravate blemishes so overall formulation and skin condition still matter.
Summary
Sd Alcohol 39-A acts as an astringent that momentarily tightens the look of pores a solvent that dissolves oils resins and fragrance components and a viscosity controller that lightens textures and speeds dry-down. Its fast evaporation and budget-friendly cost kept it popular for decades in toners sprays and quick-dry nail or hair products although interest has dipped slightly in recent years as some brands shift toward alcohol-free claims.
Used at typical cosmetic levels it is considered safe for most skin types with the main caveat being potential dryness on sensitive or already parched skin. As with any new skincare or makeup formula it is smart to patch test first so you can gauge your own tolerance before applying it more broadly.