Perfumer's alcohol: what SDA 40-B is and what you can use instead

After the fragrance oil itself, the alcohol raises the most questions for people making perfume at home: which one, what proof, and whether something from the liquor store or the pharmacy will do. This article covers only the alcohol side of the base. The full process is in how to make perfume at home with fragrance oil.

What perfumer's alcohol is

Perfumer's alcohol is high-proof ethanol that has been denatured, meaning something has been added to make it undrinkable. In the US the most common grade is SDA 40-B (specially denatured alcohol, formula 40-B), usually sold at around 190 proof, which is 95% alcohol by volume. The rest is water.

The formula is set in federal regulations (27 CFR 21.76): per 100 gallons of alcohol, a small amount of denatonium benzoate and tert-butyl alcohol. Denatonium benzoate is intensely bitter, but at that level it adds practically no scent. That is what makes 40-B suitable for perfume, where other denatured alcohols are not: the denaturants were chosen not to smell.

Its job in a perfume is to dissolve the oil and carry the scent off the skin as it evaporates. It should not leave an odor of its own. If a new blend smells strongly of alcohol in the first days, the cause is more often the lack of rest than the alcohol itself; see why homemade perfume smells like alcohol.

Substitutes: what works and what doesn't

Everclear and other grain alcohol

Undenatured 190-proof grain alcohol is chemically close to perfumer's alcohol and is a common substitute. The catch is practical: it is sold as liquor, so it carries liquor tax and its availability depends on state law. The 151-proof version contains more water, which you would need to account for if you add water to your base.

Why vodka doesn't work well

At 80 proof, vodka is 40% alcohol and 60% water. Much of the fragrance oil won't stay dissolved in that much water, so the blend can turn cloudy or leave an oily layer. On skin it evaporates slowly and the scent carries less. A small amount of distilled water can go into a perfume, but it is easier to control when you add it yourself to high-proof alcohol.

Is perfumer's alcohol toxic?

Not in the way it is meant to be used. SDA 40-B is the grade used in commercial perfumes and many cosmetics; the denaturants are there to make it undrinkable, and it is not for drinking. Like any alcohol it can dry or irritate sensitive skin, so patch-test a new blend. The real hazard is the methanol in fuel-type denatured alcohol described above, which is why the composition on the label matters.

190 proof or 200 proof?

Most perfumer's alcohol is around 190 proof, which is plenty for home perfumery. 200-proof (anhydrous) ethanol is also available. With almost no water in it, it gives you tighter control if you add water yourself. It costs more, and once opened it slowly absorbs moisture from the air. If you use a premixed base, the choice has already been made for you.

How to check an alcohol for odor

Ethanol has a faint smell of its own. What matters is that nothing stays behind once it evaporates. A simple check:

1. 1Put a few drops on a perfume blotter or a clean strip of paper.
2. 2Ignore the first sharp hit of alcohol and wait a minute or two.
3. 3Smell the strip again. Good perfumer's alcohol leaves almost nothing. A plastic, sweetish or medicinal note that lingers means the alcohol may not suit perfume.

Repeating this with each new bottle makes it easier to tell what changed if a later batch turns out differently. Some products sold as perfumer's alcohol already contain additives such as a fixative; if the listing doesn't say, ask the supplier.

How much alcohol you need

The amount follows from your concentration. At 20% in a 50 ml bottle, you need 10 ml of fragrance oil and 40 ml of base. If you build your own base, that 40 ml is split between alcohol, distilled water and fixative. If you work by weight, remember that ethanol is about 0.789 g/ml, so 40 ml of alcohol weighs about 31.6 grams. More on the conversion in fragrance oil grams to ml.

Storage

Perfumer's alcohol is flammable and evaporates quickly. Keep it in a tightly sealed bottle away from heat and direct sunlight. A cap left off lets alcohol escape and lets moisture in, which lowers the proof over time. If you bought a large jug, decanting a small glass bottle for daily use saves opening the main container.