The materials you bought too much of: a table converting regret into trial counts

A thread asked which material people bought too much of and barely used. Thirty-one replies named seventeen materials, with gram figures attached. I converted each against the median dose across 954 formulas: 10 g of indole makes 333 five-gram trials, 25 g of floralozone makes 1,250, and 250 g of benzyl butyrate makes over seven thousand. Thirteen of the seventeen have a median dose at or below 1%. And money is only part of the cost — 75.2% of database materials state a shelf life of two years or less, and 176 of the 263 IFRA standards were published or last revised in 2020 or later.

Someone asked r/DIYfragrance a question that turns out to be very answerable:

"What fragrance material did you buy too much of and barely end up using? I'm curious because some materials sound like they'll be useful in everything, then once you actually start blending with them they end up sitting on the shelf forever."

Thirty-one replies, and people were admirably honest about the gram figures.

Those numbers convert. I took each material against the median dose across the 954-formula corpus and worked out how many five-gram trials it makes.

The short version

Of the 17 materials named, 13 have a corpus median dose at or below 1%. That is not a coincidence; it is the answer to the question.
Ten grams of indole makes 333 five-gram trials. That user said they had used 0.5 g in a year and a half — consistent with the corpus median of 0.60%.
Twenty-five grams of floralozone makes 1,250. They bought it because fifteen dollars looked like a good price.
Two hundred and fifty grams of benzyl butyrate makes over seven thousand. That user reported using 1 g in a year.
Money is only part of the cost. Of the 1,303 database materials carrying a stated shelf life, 75.2% state two years or less.
And an old material does not simply weaken: what oxidation produces is the sensitizer, on a century of evidence.
Then there is regulation. 176 of 263 IFRA standards (66.9%) were published or last revised in 2020 or later, and two people in the thread lost a kilo and two kilos respectively.

About a 9 minute read.

The conversion table

The last column is: ten grams of that material, at the corpus median dose, makes this many five-gram trials.

Material	Formulas	Median dose	10 g → five-gram trials
Indole	102	0.60%	333
Calone	31	0.91%	220
Aldehyde C-8 (octanal)	39	0.92%	217
Aldehyde C-9 (nonanal)	34	0.48%	416
Aldehyde C-10 (decanal)	128	1.00%	200
Aldehyde C-11	108	1.00%	200
Aldehyde C-12 MNA	60	1.00%	200
Floralozone	23	0.40%	500
Rose oxide	76	0.50%	400
Skatole	5	1.00%	200
Benzyl butyrate	1	0.70%	288
Methyl anthranilate	116	0.85%	235
Triplal / ivy carbaldehyde	94	0.60%	333
Ethyl acetate	80	1.50%	133
Guaiacol	7	3.75%	53
Sandalore / sandalwood types	131	2.63%	76
Tonalide	13	3.00%	67

Put in the quantities they actually bought and it gets clearer:

What the user said they bought	Five-gram trials at the median dose
10 g indole	333
25 g floralozone	1,250
50 g calone	1,099
100 g Sandalore	760
100 g ethyl acetate	1,333
250 g benzyl butyrate	over 7,100

Seven thousand five-gram trials. At three a week, that is forty-five years.

What those 13 have in common

Thirteen of the seventeen carry a median dose at or below 1.00%.

This is the cautionary version of the rule we wrote before: before ordering, ask what percentage you will use it at.

Why that rule is hard to follow got stated in the thread:

"Floralozone — I use it all the time but in such small quantities that there was no reason for me to buy 25 grams, but it was 15 bucks which seemed like a good price."

"Cheap" is priced per bottle; "enough" is counted in trials. Those are different units, and the shop only shows you the first.

Another put it plainly:

"Cheap at 30ml is dangerous logic when you're starting out — suddenly you have a lifetime supply of materials you barely use."

One person offered an executable rule worth copying:

"I have a rule in my lab, never buy any raw for more than 10 × 100 ml @ 20%, unless the difference between say 5g and 15g is $3 then I buy the slightly higher qty."

What makes that rule smart is that its unit is finished product, not grams in a bottle.

The second cost: time

Money is only part of it. Material you cannot use up spoils.

Counting the 1,303 database materials carrying a stated shelf life:

Stated shelf life	Materials	Share
12 months	397	30.5%
18 months	21	1.6%
24 months	561	43.1%
36 months	111	8.5%
48 months	10	0.8%
60 months	3	0.2%
Other	200	15.3%

75.2% state two years or less. Only 9.5% state 36 months or more.

Someone six years into the hobby wrote:

"I'm pretty sure a lot of materials should be thrown out after about 3–4 years, especially if they're stored with the caps that vendors typically ship them with."

The suppliers' own figures are stricter than that. Two years, not three to four.

(Their observation about caps is worth keeping: they suggested that more airtight caps — the larger push-and-twist ones — might extend storage. I have no data to test that, but the direction agrees with headspace and how often a bottle is opened.)

An old material does not merely weaken

This is the part most worth stating, because the thread's discussion stops at "it loses potency".

Losing potency is the good half. The bad half is that it becomes something else.

Karlberg and Lepoittevin published a review in Contact Dermatitis in 2021 titled "One hundred years of allergic contact dermatitis due to oxidized terpenes".

Attention to sensitizing terpene oxidation products tends to settle on oxidized limonene and linalool, they note, but the autoxidation of terpenes in relation to allergic contact dermatitis is not new — it dates to the early twentieth century, when turpentine caused occupational contact dermatitis in painters.

The researchers of that era concluded that the main culprit in Scandinavian turpentine was Δ3-carene hydroperoxides. That explains its high sensitizing effect compared with French turpentine, which is of the Iberian type with no or only traces of Δ3-carene.

Two further conclusions are worth keeping:

Historical exposure showed that ending the industrial exposure stopped the occupational skin sensitization.
Patch test studies demonstrated that monoterpene hydroperoxides are a common cause of contact allergy in the population, rather than an obsolete source tied to turpentine alone.

Their closing line: a hundred years of extensive chemical and clinical studies worldwide should be sufficient to meet the evidence requirement regarding allergic contact dermatitis caused by terpenes.

What that means for the three-year-old citrus oil on your shelf: part of its limonene has become hydroperoxides, and those hydroperoxides sensitize more strongly than the limonene did. What you are using is not what you bought three years ago.

The other study we have cited measures the same thing on a different material: Hagvall and colleagues found in 2007 that air-exposed geraniol samples had moderate sensitizing capacity, quite different from that of pure geraniol.

So "it will not hurt to keep it" is wrong. Keeping it turns it into something with a different sensitizing profile.

The third cost: regulation

One person's loss in the thread was the most dramatic:

"A kilo of amber core just as the restriction hit. Oh and like 2 kilos of tonalide just in time for the EU to go crazy over it."

That is not bad luck; it is a probability.

I parsed the publication or last-revision year of the 263 standards in IFRA's public standards index:

Year	Standards
2020	116
2023	59
2006	32
2008	23
2004	10
All other years combined	23

176 (66.9%) were published or last revised in 2020 or later.

Read that number carefully. The 116 in 2020 most likely reflects the mass revision of Amendment 49 — one amendment re-dates many standards at once. So this measures when the current text was issued, not how often a given material's status materially changed.

But for purchasing the implication holds: if you buy a kilo today, the document governing it will probably be reissued before you use it up.

And the last article hit the same fact from another side: of five Schiff bases in the database, two are built from aldehydes (Lilial and Lyral) that have since been banned.

The more you buy, the longer you are locked in, and the rules move during that time.

The one bought three times

One more reply deserves its own note:

"I also purchased large quantities of terpineol alpha acetate THREE TIMES before I realized different vendors use different names and descriptions."

This series has now hit that same problem five times — omega-pentadecalactone's four names, helional's five, Vertofix's three, eucalyptus oil and cineole being two names for different things, and Lilial filed as lilyall.

This is the first time I have seen someone pay for it three times over.

Check your existing stock by CAS before ordering. That takes thirty seconds.

An executable rule

Collapsing the four points into one:

Before buying, work out how many trials the bottle makes, rather than what the bottle costs.

Concretely:

Look up the material's median dose. The table of 79 common materials is here.
Decide your trial size. Two to five grams is enough.
Compute the count. Grams ÷ (median dose × batch weight).
Divide by your frequency. If the answer exceeds two years, buy the small size — because three quarters of materials state a shelf life of two years or less.
Match on CAS. Confirm you do not already own a bottle of it under another name.

What this doesn't establish

Corpus median doses are not your doses. Those 954 are public demo formulas, 74% carrying a patent or source field, and they carry those documents' habits. Your own formulas may differ substantially, especially if you are deliberately building around a material.

"How many trials" is arithmetic, not a forecast. It assumes you use the median dose every time, make five grams every time, and waste nothing. In practice there is loss, there are failed batches, and there are directions you will not revisit.

Shelf life is the supplier's stated figure, not a measured failure point. It is a conservative recommendation, not "it spoils on day 731". And the database's shelf life field covers only 1,303 records out of 42,225.

The IFRA year distribution has a large limitation. A mass amendment updates many standards' dates at once, so the 116 in 2020 does not mean 116 materials changed status that year. I measured document publication dates, not the frequency of substantive change. Answering the latter would require diffing versions standard by standard, which I did not do.

Purchase and usage quantities in the thread are self-reported. "0.5 g in a year and a half" cannot be verified; I compared it against the corpus median to check that the direction agrees, not to validate that person's records.

Karlberg is a review rather than primary research, and it concerns terpenes. It does not generalise to all fragrance materials — something like Vertofix with an extremely low vapour pressure ages differently.

References

A. T. Karlberg, J. P. Lepoittevin, One hundred years of allergic contact dermatitis due to oxidized terpenes: What we can learn from old research on turpentine allergy, Contact Dermatitis, 85(6), 627–636 (2021). PMID 34453446. doi:10.1111/cod.13962

L. Hagvall et al., Fragrance compound geraniol forms contact allergens on air exposure, Chemical Research in Toxicology, 20(5), 807–814 (2007). PMID 17428070. doi:10.1021/tx700017v