Material guide: ethanol — the one that is 80% of the finished product, and it has a smell

Short version: the largest material by volume in your finished product, and most people do not treat it as a material. It has a smell, it leaves extremely fast, and it is the most flammable thing this series has covered.

The fields

Field	Value
CAS	64-17-5
Head synonym	ethyl alcohol
Formula	C2H6O, MW 46.07
Database category	Carrier solvents/diluents for flavor and/or fragrance agents; extraction solvent
Appearance	Colorless clear liquid (est)
Boiling point	78–79 °C @ 760 mmHg
Melting point	−115 to −114 °C
Flash point	9.44 °C
logP	−0.10 (est)
Specific gravity	0.772–0.786 @ 25 °C
Vapour pressure	44.6 mmHg @ 20 °C
Odour strength	Medium (rank 2)
Odour	Alcoholic, ethereal, medicinal
Substantivity	< 1 hour at 100%
Water solubility	1.00E+06 mg/L @ 25 °C (exp) = miscible
Suppliers	41
Regulatory	JECFA 41, FEMA GRAS 2419, CoE 11891, FLAVIS 02.078
Cosmetic uses	Antifoaming agents, antimicrobial agents, astringents, fragrance, solvents, viscosity controlling agents
Oral toxicity	Rat LD50 7,060 mg/kg
Dermal toxicity	Rabbit LDLo 20,000 mg/kg
Inhalation toxicity	Rat LC50 20,000 ppm/10H

Three solvents side by side

This series covered TEC (article #84) and DPG (article #90). This is the third, and it is not the same kind of thing.

	Ethanol	DPG	TEC
Molecular weight	46.07	134.18	276.29
logP	−0.10	−0.60	0.10
Vapour pressure @ 20–25 °C	44.6 mmHg	0.0319	0.000175
Substantivity	< 1 hour	400 hours	216 hours
Flash point	9.44 °C	118.33 °C	118.33 °C
Odour strength	Medium	None	None
Role in the finished product	Carrier (about 76%)	Diluent (inside the concentrate)	Diluent (inside the concentrate)

Vapour pressure differs by five orders of magnitude. Ethanol's 44.6 mmHg is 250,000 times TEC's, and four times that of the fastest fragrance material this series has covered (hexanal, at 10.888).

That is the fundamental difference from the other two: DPG and TEC stay in the formula; ethanol leaves. Its job is to carry things onto skin and disappear.

It has a smell

This field deserves its own section, because the forum asks repeatedly.

The same subreddit has a thread called "The bite of ethanol" with 26 replies, another asking whether perfumer's alcohol beats Everclear's strong alcohol smell, and a German hobbyist writing that their 96% cosmetic base water smelled bad and only became acceptable after three months of maceration.

The database's answer is that ethanol's odour strength is medium, rank 2.

Odour field: alcoholic, ethereal, medicinal. Odour description at 100%: strong alcoholic, ethereal, medical.

It is not an odourless background; it is a medium-strength material with a medicinal lean.

And the substantivity field reads < 1 hour.

This series has handled several > lower bounds — Tonalide's > 400 hours, sotolon's > 400 hours at 3% in PG, isobutyl quinoline's > 48 hours. This is the first upper bound. Same rule: < means nobody reported the actual value, only that it is under an hour.

So the bite is real, and it leaves within the hour. Which is part of why maceration is recommended so often, though maceration changes more than ethanol's departure.

190 and 200 proof are written in the grades field

The database's formulations field lists its commercial grades:

"grades: usp (95% by vol); absolute; pure; completely denatured; specially denatured; industrial, various proofs."

The USP grade is written as 95% by volume, which is 190 proof. And absolute (anhydrous) is a separate grade.

This round's beginner article handles the 190 versus 200 question. In brief: 190 proof sits near the ethanol-water azeotrope, and reviewing ethanol separation technology in 2022, Naidu and colleagues state the mechanism directly — "conventional distillation is featured by low energy efficiency and inability to separate azeotropic mixtures". Getting past that point takes something other than distillation, which is why 200 proof costs more.

And those five points are nearly horizontal on the solubility curve. Article #49 computed this from the seven materials with multi-point data: benzyl benzoate changes twofold between 90% and 95%, and a thousandfold between 45% and 95%.

It is also an antimicrobial

The cosmetic uses field lists six items, and one is easy to overlook: antimicrobial agents.

That matters for finished products. A perfume at high ethanol strength is self-preserving, which is why traditional alcoholic perfumes need no added preservative. Lower the ethanol strength — add water, make a body spray, go oil-based — and that protection goes.

Someone on the same subreddit asked how to preserve a body spray of 70% distilled water, 20% witch hazel and 10% fragrance. That formula's ethanol strength is not enough to self-preserve, and witch hazel's alcohol content does not make up the difference. This field is where that question starts.

(To be clear: the concentration, contact time and organisms required for antimicrobial effect are a separate literature that this article does not address. The field is listed to point out that ethanol is not only a solvent in a formula.)

That flash point

9.44 °C.

The lowest of any material this series has covered, and not by a little: hexanal 32.22 °C, guaiacol 82 °C, TEC and DPG both 118.33 °C, isobutyl quinoline > 100 °C.

A flash point of 9.44 °C means its vapour can ignite in an environment at ten degrees Celsius. Every indoor space anyone lives in is above that.

In practice:

• Never open or decant near a flame, an electric heater or a gas hob. This is not a "be careful" matter; it produces flammable vapour continuously at room temperature.
• Ventilate. The inhalation toxicity is rat LC50 20,000 ppm/10H, which is not an issue in normal use, but bulk decanting raises the concentration in a room.
• It is more dangerous than any fragrance material you are blending. Worth writing down, because attention usually goes to sensitisation instead.

It barely appears in the corpus

Across 954 published formulas, ethanol appears as a standalone entry once.

For comparison: DPG 445 times, benzyl benzoate 44, TEC 5.

Not because formulas do not use ethanol, but because published formulas are concentrates. Ethanol goes in afterwards, outside the formula table. This matches what this series measured in article #46: a formula that writes TEC as a line is the minority; most let the solvent vanish outside the arithmetic.

So every published formula you read omits the largest material in the finished product.

The part that happens on skin

In 2025, Hadjiefstathiou and colleagues published a device in Talanta for measuring perfume release in the air above a surface. They used a perfume of eight fragrance molecules in ethanol, measured headspace evaporation by solid phase microextraction with gas chromatography, and compared four surfaces: chemically inert glass, the Strat-M® model, a perfume test strip, and skin on volunteers' forearms.

The paper reports the device demonstrating originality, effectiveness and repeatability in vitro and in vivo, with promising results towards understanding the evaporation of fragrance molecules and its link with the physicochemical properties of skin.

Note the year: 2025. How a perfume evaporates on skin is still at the stage of establishing measurement methods. That is also why blotter and skin give different answers, and why forum arguments about it rarely settle.

(This paper did not measure ethanol strength or compare proofs. I cite it for the state of the measurement tools.)

Whether to use it

There is no "whether" for this one, only a choice of grade:

• 190 proof (USP, 95% by volume) is the standard, because it is where distillation gets cheaply.
• 200 proof does no harm, it just costs more, and it absorbs water back towards the 190s once opened.
• Denatured or not is a regulatory and eligibility question. SDA 40B is the common US specification. It differs by country and this article does not cover it.
• Off-smelling batches are real. Many report them, and ethanol's own odour field says "medicinal", so "ethanol smell" and "bad batch" are hard to tell apart. Run a blank strip of just the ethanol.
• Store it away from ignition sources. Flash point 9.44 °C.

What this doesn't establish

• The < 1 hour substantivity is an upper bound. The actual value is unknown, and the database does not document how it was measured.
• "Medium" odour strength is the database's rating. This series has already measured that only 1.9% of database materials carry a recommended evaluation strength and that the rating method is undocumented.
• I did not look up effective concentrations for the antimicrobial field. What strength, contact time and organisms ethanol's antimicrobial action requires is a separate literature this article does not address. The field is listed to note that it exists.
• The azeotropic composition figure is a textbook value, not mine. Naidu 2022 establishes the mechanism, that ordinary distillation cannot separate azeotropes.
• Hadjiefstathiou 2025 measured neither ethanol strength nor proof. It is cited for the state of skin-evaporation measurement.
• Ethanol appearing once in the corpus is a notation artefact, not a usage figure. Published formulas are concentrates.
• Denaturants and their effects are entirely absent here. Different denaturing formulations (SDA 40B, SDA 39C and others) contain different additives which affect smell, and this article did not look into that.