He asked whether one or two would do. The forum named forty

Someone posted a question with clear boundaries on r/DIYfragrance. He was building a "gothic ocean" for his girlfriend, who said it was not dirty enough. He listed the seven materials he had, then wrote:

"I'm considering getting some combination of: Martima, oceanol, algenone, and Dimethyl sulfide. I just don't want to spend more than is necessary for what I suspect can be solved without buying all four products."

He asked again a little later:

"Do you think they're all necessary, like could I get away with one or two?"

Thirty-six replies produced 42 material mentions, 40 distinct after merging duplicates.

He asked whether he could buy fewer. The forum named forty.

The short version

• That thread named 40 distinct materials, in answer to a question about buying less.
• Across 954 public formulas, the median material count is 16, interquartile range 11-23. Only 10.5% of formulas contain 30 or more materials.
• And those 16 are not evenly weighted: 9 materials carry 90% of the weight in the median formula, the top 3 carry 54.7%, and the single largest carries 25.0%.
• A 2012 PNAS study supplies a ceiling: at about 30 equal-intensity components spanning odour space, most mixtures smell alike, despite sharing no component at all.
• But that experiment's conditions are exactly the ones a formulator avoids on purpose. Real formulas escape that regime by being unequal — and 54.7% is the escape hatch.
• One material, Oceanol, got four different descriptions from four people in that thread. Nobody was misremembering: naming smells is something humans are simply bad at (Olofsson and Gottfried 2015).
• The most useful line in the whole thread was nine words: "key is getting the dosages properly dialed in."

About 9 minutes.

What forty materials looks like

Laying out what the thread offered, with duplicates merged:

Seaweed: seaweed absolute, Fucus seaweed absolute, Choya Nakh, algix synarome Marine / ozonic: Maritima, Oceanol, Algenone, Scentenal, Scentenol, dimethyl sulfide Ambergris: Ambrinol, Ambrinol 95, Ambermax 50, Ambrocenide, Fixamber, amberarome, white amber, Evernyl Animalic: indole, skatole, Tonquitone, Animalis 1745, costus Woody: Cedramber, Osyrol, Norlimbanol, Javanol, Dynamone Other: blackcurrant absolute, tobacco absolute, wormwood oil, oakmoss absolute, labdanum resinoid, styrallyl acetate, rose oxide, Mefrosol, Rose Crystals, caraway, salicylates, Hedione

One commenter listed 13 on their own, then added another 6.

Nobody there is being unhelpful. Every one of those is a material somebody genuinely finds useful. The problem is that forty sincere suggestions add up to an answer to a different question.

How many materials fit in one formula

There are numbers for this. Across the 954-formula deduplicated corpus, solvents excluded:

	Value
Median material count	16
First quartile	11
Third quartile	23
Largest formula	56
Formulas with ≥ 30 materials	100 (10.5%)
Formulas with ≥ 40 materials	26 (2.7%)

The thread named more materials than 89.5% of published formulas contain in total.

And he already had seven.

The next table matters more, though, because the count is not the point — the weight distribution is:

	Median
Materials carrying 90% of the weight	9
Top 3 as a share of total weight	54.7%
Largest single material	25.0%

In a typical formula, nine materials settle nine-tenths of the weight, and the top three settle more than half.

The other seven or so are not unimportant — we've written about what trace materials do — but they are modifiers, not structure.

What he is missing is not materials eight through forty-seven. It is a decision about which three come first.

What happens past thirty

There is an experimental result worth knowing here, because it puts a ceiling on the habit of adding one more.

Weiss and colleagues ran a clean analogy experiment in PNAS in 2012. In vision, many wavelengths at equal intensity give "white". In audition, many frequencies give "white noise". What about smell?

They selected 86 molecules spanning olfactory stimulus space, diluted each to roughly equal intensity, mixed them into combinations with varying numbers of components, and asked people to rate how similar pairs of mixtures were.

The result:

As the number of nonoverlapping, equal-intensity components in odorant mixtures increased, the mixtures became more similar to each other, despite not having a single component in common. With ~30 components, most mixtures smelled alike.

And not merely similar. After participants were acquainted with an arbitrarily named mixture of about 30 equal-intensity components, they later applied that name more readily to other novel mixtures of about 30 equal-intensity components, but not to mixtures with fewer components or to ones that did not span stimulus space.

They called the shared percept "olfactory white".

This reads like "over thirty materials turns to grey mush", and that is not what the paper says, and the difference matters.

The effect requires two conditions: equal intensity, and spanning odour space.

Those two conditions are precisely what a formulator avoids on purpose.

• Components in a formula are not equal intensity — the median formula's largest material is 25.0% and its top three are 54.7%.
• Components in a formula do not span odour space — they are deliberately clustered in a few regions.

So 54.7% is more than a descriptive number. It is the escape hatch. A formula keeps a recognisable character precisely because it is wildly unequal by weight.

And the habit of adding one material at a time, a little of each, walks toward both conditions.

(To be clear: that experiment used single molecules diluted to equal intensity, not perfumes. I cannot show that a 40-material perfume falls into the regime they measured. I cite it to show the regime exists and what the entry conditions are.)

One material, four descriptions

One exchange in that thread deserves attention. The poster asked what Oceanol smells like, and four people answered:

Who	What they said
Hot_Spread2659	"super saline, mineral and salty"
Zeta-Splash	"more similar to Veramoss… it's not the star of the show"
kdoughboy12	"very strong and persistent, smells of straight up salt to me, or maybe clean ocean air, it doesn't feel very dirty"
Hot_System4328	"very iodine-esk… the same scent that you get after washing your silverware in a dishwasher that needs to be cleaned"

Mineral, mossy, salt, iodine. Four people, four directions.

And it is likely that none of them is misremembering.

Olofsson and Gottfried reviewed this in Trends in Cognitive Sciences in 2015, and their opening sentence is:

Most people find it profoundly difficult to name familiar smells.

The key point follows: this difficulty persists even when perceptual odour processing and visual object naming are unimpaired, implying that the problem sits in the interaction between the senses and the language system. Their framework splits the difficulty across three successive stages: object perception, lexical-semantic integration, and verbalisation.

Those four people may not have different noses (though they might). The step from "what I smelled" to "a word" leaks on its own.

Which has a direct consequence for reading forums: a verbal odour description is the lossiest link in the chain. "Iodine-esque" and "straight up salt" may be pointing at the same thing, or not, and the text cannot tell you which.

(We've written about individual differences. This is the other half: two people who smell the same thing may still write different words.)

"Is Ambroxan salty"

The same thread has a smaller, cleaner example.

• The poster: "I just barely detect the salt aspect of Ambroxan and it's already decent part of the formula."
• kdoughboy12: "Ambroxan doesn't smell salty to me."
• Crst80: "Another thing to consider is that ambroxan and ambrocenide give a strong salty effect."

Three people, three answers, about one property of one material.

The move here is not to take a vote. It is to smell it yourself. Which is what the poster was already doing — he was reporting his own observation rather than repeating someone else's.

The most useful line in the thread

Among forty recommendations, the most useful advice was one sentence, and it was not a material name.

Crst80 wrote:

"Lots of good suggestions — i'd say key is getting the dosages properly dialed in."

That answers the question he actually asked. He has seven materials, a clear target (dirtier, saltier), and he was asking whether to buy more.

The answer is: reproportion the seven first.

And the corpus backs that direction. The top three carry 54.7% — changing the ratio among your top three moves the finished thing more than adding an eighth material does.

A procedure for converging

Collecting the above into something to do. Every step exists to make you buy less.

1. Write down the word you are after. His girlfriend said "dirty" and he said "saltier". Those are two directions, not one. Handle them separately.

2. Sort your current formula by weight and look at the top three. If the quality you want is not among them, that is a ratio problem rather than a shortage of materials.

3. Change one variable at a time. We've written about how easily a control test gets contaminated. Add a new material while adjusting three old ones and you will not know afterwards which step helped.

4. If you do buy, buy the one with the most agreement. Only a handful in that thread were named by more than one person independently: seaweed absolute, Choya Nakh, Ambrinol, Maritima, Oceanol. Repetition is the closest thing to signal in a thread like this.

5. Look up the recommended dilution before you buy. The database's note for dimethyl sulfide reads "recommend smelling in a 0.10% solution or less" — the most extreme one this series has met. Buy it neat and sniff it and you will lose an afternoon.

6. Accept that you may have to smell it to know. Two people in that thread wrote versions of the same sentence: the honest answer is to get small amounts and smell them yourself. That is not a brush-off; it is the only reliable answer to this question.

What this doesn't establish

The count of forty is mine, done by hand. I merged obvious duplicates (Ambrinol with Ambrinol 95, Animalis with Animalis 1745), and some names I could not confirm refer to the same thing — Scentenal and Scentenol both appear in the thread. Take that number as forty plus or minus two or three.

"Forty is more than 89.5% of formulas contain" compares two different things. The thread is a list of suggestions rather than a formula, and nobody claimed he should buy them all. I use the comparison for a sense of scale, not as an accusation.

The corpus material counts exclude solvents, and formulas differ in what they record as one material (pre-dilutions, compounded bases). That median of 16 is this record set's median, not an industry standard.

Weiss's conditions were stated above and bear repeating: equal intensity, spanning odour space. A perfume meets neither. I cannot infer from that paper whether any actual perfume turns into "olfactory white".

The 86 molecules and the roughly 30-component threshold come from their stimulus set and their participants. A different set of molecules or people need not put the threshold in the same place.

Olofsson's paper is a review of the general difficulty of naming, not an account of what those four people experienced. I cannot tell whether they smelled different things or smelled the same thing and reached for different words. That is exactly the point: the text cannot tell you.

I have smelled neither Oceanol, Maritima, Choya Nakh nor anything else in that thread. Every quotation above is someone else's observation and I have verified none of them.

"Repetition is close to signal" is a rough heuristic rather than a method. A material may get named by several people because it is cheap, widely stocked, or featured in a popular tutorial.

References

T. Weiss, K. Snitz, A. Yablonka, R. M. Khan, D. Gafsou, E. Schneidman, N. Sobel, Perceptual convergence of multi-component mixtures in olfaction implies an olfactory white, Proceedings of the National Academy of Sciences, 109(49), 19959-19964 (2012). PMID 23169632. doi:10.1073/pnas.1208110109

J. K. Olofsson, J. A. Gottfried, The muted sense: neurocognitive limitations of olfactory language, Trends in Cognitive Sciences, 19(6), 314-321 (2015). PMID 25979848. doi:10.1016/j.tics.2015.04.007

Related: how big is the palette, his control test lied to him for a year, individual differences, which trials to keep.