White particles in the bottle: eight incompatible explanations, and a test you can run yourself

Someone posted two photos to r/DIYfragrance:

"I bought this perfume about a month ago (from an Australian clone house) and recently noticed a strange strand-like object floating in the bottle, along with quite a few cloudy white particles dispersed throughout the liquid. I've never seen anything like this in a fragrance before... I'm obviously hesitant to spray it on my skin until I know what it is."

Thirty replies. Between them, at least eight answers that cannot all be right:

Claim	Votes
A hair, plus air bubbles clinging to dust	80
A micelle line — undissolved droplets separating from the alcohol	24
Precipitation from ethanol loss or a drop in temperature	3
Unfiltered natural particulates clumping together	5
Mould	1 (two people, once each)
Too much DPG or glycerin	1
A crystalline material like tonalide dropping out of saturation	1
Copal resin solidifying in the cold	1

That spread is the reason to write this one up. Nobody there is being careless. A few of those claims can be checked against data, and checking shortens the list.

The short version

• "Something drops out when it gets cold" is supported. Of the 460 materials in our database with 20+ suppliers and a recorded melting point, 255 (55.4%) melt above 20 °C — solid at room temperature to begin with.
• Both materials named in the thread check out: orris butter melts at 40-46 °C, copal at 90-140 °C.
• "Micelle line" is the wrong term. Micelles require a surfactant above a critical concentration, and an ordinary fragrance formula contains none. What was described (undissolved droplets separating) is emulsification or precipitation.
• The real mechanism has a name and a literature: nanoprecipitation, popularly the "Ouzo effect" — a hydrophobic compound entering a non-solvent forms a dispersion of particles without any surfactant at all.
• Mould is the least likely of the eight. Someone in the thread said so, and their reasoning holds.
• One reply pasted in "the AI response about this". The pasted text is accurate, and it also does nothing for the person asking.

About 9 minutes.

How often does something actually drop out

Start with the checkable claim.

I pulled every material with 20 or more suppliers and a recorded melting point — 460 of them:

Melting point	Count	Share	Meaning
≥ 20 °C	255	55.4%	solid at room temperature
≥ 4 °C	295	64.1%	solidifies in a fridge
≥ 0 °C	304	66.1%	—

More than half are solid at room temperature.

The ones sitting closest to room temperature are the ones that catch people out when the weather turns:

Melting point	Material	Suppliers
17-18 °C	decanal (aldehyde C-10)	92
16.6 °C	acetic acid	82
17-18 °C	gamma-dodecalactone	82
16-17 °C	octanoic acid	68
17-19 °C	dimethyl anthranilate	64
17-20 °C	glycerine	64

Seventeen degrees. That is an ordinary winter room in a lot of houses. And the top row, decanal, has 92 suppliers, which makes it one of the aldehydes people buy in their first week rather than something obscure.

The last row is worth a second look. Somebody in the thread guessed at too much glycerin, and glycerol's own melting point is 17-20 °C. Glycerol supercools famously well, though, so in practice it almost never crystallises and stays a viscous liquid — a clean demonstration that a melting point and what happens in your bottle are two different questions.

The two materials named in the thread both check out:

• Orris rhizome concrete butter: melting point 40-46 °C. Whoever said some orris butters solidify in the cold was right — it is liquid only above body temperature.
• Copal resin: melting point 90-140 °C. Whoever asked whether the formula contained copal was asking a good question. (Copal has only 2 suppliers in the database, below the threshold for the 460, so that melting point comes from a full-database lookup and sits outside the statistics above.)

So "it got cold and something came out of solution" is a common, quantified situation rather than a guess.

(This series has covered exaltolide at 34-38 °C and Calone at 38-41 °C; ethyl vanillin arrives as a powder. There are more solids on a working palette than most people expect.)

About that "micelle line"

The second-highest-voted answer, stated with real confidence:

"That's not a hair, and it's not a dirty bottle... It's called a micelle line! It's a chain of undissolved droplets trying to separate from the alcohol. Caused by low-quality oils, an overloaded formula, or too much water in the fragrance oil. You can add a little IPM or PS20 to hold solubility."

The same person added later: "I'm only nine months in and this was one of the first things I learned about maceration... I thought this sub was for perfumers?"

The description of what is happening is right. The name is wrong.

Micelles belong to surfactants. They need amphiphilic molecules — a water-loving end and an oil-loving end — that spontaneously assemble into spheres once concentration passes the critical micelle concentration. An ordinary fragrance formula has no surfactant in it: fragrance materials dissolved in ethanol, with nothing playing that role.

What was described, droplets coming out of solution, is emulsification or precipitation, which is a different physical event.

And the real mechanism is well studied.

Lepeltier and colleagues reviewed nanoprecipitation and the "Ouzo effect" in Advanced Drug Delivery Reviews in 2014. The name comes from the aniseed spirit: pour the clear liquid into water and it turns milky on contact.

Their description: under appropriate conditions, nanoprecipitation of a hydrophobic compound in a non-solvent yields a dispersion of nanoparticles with a narrow size distribution, without the use of surfactant (the "Ouzo" effect).

The review's subject is the main parameters governing nucleation and growth of aggregates in a supersaturated solution, and it stresses that mixing kinetics matter.

Note the phrase "without the use of surfactant". That is exactly the line between this and micellisation: micelles need a surfactant, the Ouzo effect does not. What happens in a perfume bottle is the second one.

The advice to add IPM or PS20 is itself sound — those are solubilisers and they do improve solubility. The reason they work is simply not the reason that was given.

About the mould

Two people raised mould. Someone in the thread pushed back immediately:

"Molds can't possibly present in alcohol, that's probably dust and hair. I had the same, an ant somehow got into my perfume."

That pushback points the right way. Ethanol at sufficient concentration is a broad-spectrum antimicrobial, and a perfume sits far above what ordinary microbes tolerate.

(Gold and colleagues' StatPearls review summarises the efficacy of alcohol-based sanitisers and what it depends on — alcohol type, amount, and consistency of use. That review is about hand hygiene, not perfume, and I cite it only for the established antimicrobial action of ethanol, not to transfer any hand-sanitiser number to a bottle of fragrance.)

There is one exception worth naming. If the bottle is low in ethanol and high in water — someone in the thread wondered whether it might be heavily water-based — that protection weakens. We ran the numbers on this in the glycerin piece: a water-containing product plays by different rules and needs preservation.

So mould in a normal alcoholic perfume is close to impossible, and mould in a water-based product is not. Which one applies depends on the formula, and a photo does not show the formula.

The reply that pasted in an AI answer

One person wrote:

"Looks like precipitation, which happens in higher-concentration fragrances. Could be because some ethanol evaporated, leaving a higher concentration, or because the temperature dropped (solubility falls when cold). Shaking will redissolve those components and they'll stay in solution a while. AI response about this: In perfumery, precipitation refers to dissolved components coming out of solution, forming visible flakes, cloudiness, or sediment at the bottom."

The AI definition is correct. That is what precipitation means.

It also does no work. It replaces a word with the definition of that word, when the question on the table was which of eight things is in this particular bottle.

It is a clean example of what we wrote about last time: the checkable part (a definition) and the uncheckable part (a diagnosis of your bottle) sit in the same paragraph in the same tone. The commenter labelled their source, which is the right thing to do — the bad version of this is the unlabelled one.

Worth noting that their own first half — ethanol loss, falling temperature, shake and it redissolves — is more useful than the pasted definition, because it is a prediction you can test.

Working out which one you have

Here is the whole thing as a procedure. Every step exists to eliminate some of the eight.

1. Hold it to the light and look at the shape.

• Long, single, curved → a fibre or a hair is likely.
• Fine particles spread evenly, whole liquid hazy → a solubility problem.
• Lumps sitting on the bottom → something dropped out, or natural residue that was never filtered.

2. Warm it in a water bath to 35-40 °C and leave it ten minutes.

• It dissolves → almost certainly temperature and solubility. One of those 255 solids.
• It doesn't → not precipitation. Think foreign object.

This step earns its place, because it splits the eight into two groups in one move. The first time a batch of mine went cloudy I spent an evening reformulating before I thought to warm the bottle; it cleared in about four minutes and the formula had never been the problem.

3. Shake it, let it settle, and watch where it comes back.

• Re-forms in the same spot every time → something there is nucleating it, quite possibly that fibre.
• Disperses evenly, then drifts down → precipitation.

The original poster described the second one: it gathers at the bottom after shaking, then rises again into a strand.

4. Read the formula. If the label lists naturals, absolutes, resins, or a material you know melts high, the answer usually appeared back at step one.

5. To rescue it: filter. A coffee filter or a syringe filter both work. Someone in the thread was right that a finished fragrance should be filtered anyway. Filtering also removes some of what you wanted, though, since those insoluble natural fractions were contributing odour.

6. If you bought it finished: go back to the seller. The most practical line in the thread was that you cannot diagnose this by guessing, so contact the vendor for a replacement. A refund costs less than spraying an unknown solid on your skin.

What this doesn't establish

I have seen nothing beyond that photo and description. Every diagnosis above is written against a text description, and I cannot say which of the eight that particular bottle is. This gives a procedure, not an answer to that person's question.

The 55.4% carries a heavy selection effect. There are 1,412 materials with 20+ suppliers, and only 460 (32.6%) have a melting point recorded at all. The database tends to record a melting point when it is meaningful, so the share of solids among those 460 is higher than the share among all materials. That number describes the recorded set and does not generalise.

A melting point is for the pure material, not the temperature at which it precipitates from solution. A material melting at 40 °C dissolved in ethanol will not crystallise at 40 °C; that depends on concentration, solvent, and everything else in the bottle. Melting points tell you which materials to suspect, not at what temperature.

Calling "micelle" the wrong word is a correction about terminology, not about the handling advice. Adding a solubiliser works.

The Lepeltier review is drug delivery, not perfumery. I cite the mechanism and the surfactant-free property of it, not their application.

The alcohol sanitiser review is about hand hygiene. I use it for the general fact of ethanol's antimicrobial action, with no number carried over.

I have not tested how many materials the warming step actually recovers. It is an operational suggestion derived from melting points, not an experimental result. Check that the container tolerates heat and keep it away from flame first — some materials have very low flash points.

References

E. Lepeltier, C. Bourgaux, P. Couvreur, Nanoprecipitation and the "Ouzo effect": Application to drug delivery devices, Advanced Drug Delivery Reviews, 71, 86-97 (2014). PMID 24384372. doi:10.1016/j.addr.2013.12.009

N. A. Gold, T. M. Mirza, U. Avva, Alcohol Sanitizer, StatPearls [Internet], StatPearls Publishing (2023). PMID 30020626

Related: storage and oxidation, maceration and water, glycerin in the wrong product, checking AI answers about fragrance materials.