Material guide: orris butter — what you buy is the percentage, not the material

CAS 8002-73-1. Forty suppliers, melting point 40-46 °C — liquid only above body heat, among the highest-melting naturals this series has covered. And the database rates its odour strength as low. Both facts have one cause: a 2024 study comparing headspace with hydrodistillation on iris rhizomes found the hydrodistillate dominated by docosane at 45.79% plus fatty acids, with irone falling from 43.74-45.76% to 24.70%. It is a mass of fatty acids with the thing you want inside it. Which is why suppliers put the content in the product name: 15%, 8% — two bottles both called orris butter can differ twofold.

Most materials in this series can be bought by name.

This one cannot.

The database's fields carry the manufacturers' actual product names:

ORRIS BUTTER ABSOLUTE 15% Orris Concrete Nat 15% Irone Orris butter reinforced 8% Blend

Three names, three numbers. And the number is what you are buying.

The short version

CAS 8002-73-1, from two main sources: Iris pallida (40 suppliers) and Iris germanica (39).
Melting point 40-46 °C. Liquid only above body heat, among the highest-melting naturals this series has covered. The appearance is a paste.
Odour strength is rated low. Pure alpha-irone is medium.
Thick and weak have one cause. A 2024 study comparing headspace with hydrodistillation on iris rhizomes found the hydrodistillate dominated by docosane at 45.79% plus fatty acids, with cis-α-irone falling from 43.74-45.76% in headspace to 24.70%.
Myristic acid melts at 54 °C and palmitic at 63 °C. That 40-46 °C is the fatty acids' melting point.
Which is why suppliers sell a content. 15% and 8% are nearly twofold apart, and both bottles say orris butter.
Irones are structurally close to ionones, and ionone sensitivity is very nearly determined by a single gene (Jaeger et al. 2013). Whether the same holds for irones, I found no study.

About 8 minutes.

Two species, two records

The database splits it in two:

	Iris pallida	Iris germanica
Record	#28848	#28843
Suppliers	40	39
Melting point	40-46 °C	—
Appearance	pale yellow to yellow paste	yellow paste to solid
Strength	low	—
Odour	woody, fatty, violet, fruity, sweet, floral, warm	orris
Occurrence	Iris pallida rhizome	Iris germanica rhizome

Supplier counts for the two species are almost equal. And one word in the pallida record's odour field deserves attention: fatty.

That word is the key to this material.

Why it is solid

Because it is mostly not fragrance.

Friščić and colleagues analysed dried rhizomes of three endemic Croatian irises in Molecules in 2024, taking volatiles two ways: headspace solid-phase microextraction and hydrodistillation.

On the oldest, irone-rich Iris pseudopallida sample:

Method	cis-α-irone	Main component
Headspace	43.74-45.76%	irone
Hydrodistillation	24.70%	docosane at 45.79%

Same rhizome. Change the sampling method and irone falls from 44% to 25%.

And what came out of the hydrodistillation side is stated plainly:

HD yielded predominantly fatty acids, including myristic, common for all studied taxa (4.20-97.01%), and linoleic (40.69%) and palmitic (35.48%) as the major VOCs of I. adriatica EO.

Myristic acid melts at 54 °C and palmitic at 63 °C.

So that 40-46 °C melting point is not irone's. It is the fat's.

Which folds two observations into one explanation:

Why is it thick? Because it is mostly fatty acids and long-chain alkanes.
Why is it weak? Because the part you want is a minority of it.

Someone on a forum asked whether orris butter at 10% in TEC is supposed to look like that, and the answer is yes — for the same reason it smells weak.

That percentage

This is why suppliers put a number in the product name.

From the database's supplier field:

Manufacturer product name	Stated content
ORRIS BUTTER ABSOLUTE 15%	15%
Orris Concrete Nat 15% Irone	15%
Orris butter reinforced 8% Blend	8%

Fifteen percent and eight percent are nearly twofold apart, and both bottles say orris butter.

That has a direct consequence for formulation. Follow somebody's formula calling for 0.5% orris butter when they used a 15% grade and you have an 8%, and you have put in half the irone they did.

There is only one question to ask before buying: what does this bottle state.

(The same class of problem as the trade names in the jasmine piece, running the other way: there, different names for different things; here, the same name for different contents. Both need the specification to resolve.)

The word "reinforced" is worth noticing too. It usually means the manufacturer added irone to the natural concrete to reach the stated figure. That is standardisation rather than adulteration. It does mean that under the phrase "natural orris butter", part of what you have may have been put there.

Why it costs what it does

Traditionally the rhizomes are aged three to five years before extraction.

The reason is chemical: fresh rhizomes contain almost no irone. Irones form by slow oxidative breakdown of triterpenoid precursors known as iridals. That process is slow and needs time.

So a large part of the price is inventory years.

Someone in the forum thread mentioned a modern route:

"I believe this specific orris butter is made by biolandes, which they use a little bit different process to extract the irones from the roots without having to age them for several years. This results in a more affordable product."

I cannot verify that — it is a process detail, absent from the database and from the papers I found. The structure of it, though — ageing being the main cost, and someone wanting to bypass it — is coherent.

How long it lasts

This is the other half of that forum thread: listed as a base note, gone in thirty minutes.

Material	Strength	Substantivity
orris butter	low	not recorded
alpha-irone	medium, 10% or less	104 hours at 100%
beta-ionone	medium, 10% or less	112 hours at 100%

Pure irone lasts 104 hours; orris butter has no substantivity record and is rated low.

Those do not conflict. The irone in orris butter is 8-15%, and the other eighty-five percent is fatty acids — which have no smell and do nothing to prolong the irone.

One commenter said "30 minutes is about right for orris butter" and another that it is often classified as a middle note rather than a base. Both are consistent with the data.

And one more observation from that thread is worth recording:

"orris tends to grow in a fragrance. It needs many months to get to its full strength."

I cannot verify that, and we've written about maceration. It is compatible with orris butter being mostly fat: a fatty phase needs time to disperse evenly in alcohol. That is a coherent guess rather than a result.

The gene question

Irones are structurally close to ionones, and the ionone side has a very clean study.

Jaeger and colleagues identified rs6591536 in OR5A1 in Current Biology in 2013, an N183D substitution explaining more than 96% of the phenotypic variation in β-ionone sensitivity, resembling a monogenic Mendelian trait.

And the paper found that sensitive people describe it as "fragrant" and "floral", while less-sensitive people describe it differently.

What that means for orris butter I do not know, and the reason should be stated.

That study measured β-ionone, not irone. They differ by the position of a methyl group, and olfactory receptors can be extremely sensitive to exactly that kind of difference — as the phenethyl alcohol piece showed for a related case. I found no matching study for irone.

So if orris butter seems nearly odourless to you, there are two possibilities: the concentration arithmetic is wrong (that piece works it out), or you are less sensitive to this molecular family. The first can be checked; the second currently cannot.

Physical properties

Property	Value
CAS	8002-73-1
Source	Iris pallida / Iris germanica rhizome
Melting point	40-46 °C
Appearance	pale yellow to yellow paste
Strength	low
Water solubility	0.4668 mg/L at 25 °C (est)
Solubility	alcohol
Suppliers	40 (pallida) / 39 (germanica)
Odour	woody, fatty, violet, fruity, sweet, floral, warm

Water solubility of 0.4668 mg/L is among the lowest this series has met — more than forty thousand times below dimethyl sulfide's 22,000. It does not enter a water phase at all.

In practice:

Warm it before use. A water bath above body temperature, or a pocket as the forum suggested.
Weigh it warm. A cold paste will not weigh accurately.
Dilute in a solvent that takes it. TEC, DPG and ethanol all work; water is zero.
Write down your bottle's stated content. It is the only number in the formula you can reproduce.

What this doesn't establish

I have not smelled it. The whole piece sets database fields against two papers.

Friščić measured three endemic Croatian irises (I. pseudopallida, I. illyrica, I. adriatica), not the raw material of commercial orris butter, and neither headspace nor hydrodistillation is how orris butter is made. Those percentages describe those samples. I use them to establish the order of magnitude — an iris rhizome extract is mostly fatty acids with irone as a minority — not orris butter's composition.

The myristic acid range of 4.20-97.01% is enormously wide, reflecting differences between three species and three methods rather than variation within one sample.

"Aged three to five years" and "iridal precursors oxidising" are my statements of background, not drawn from either cited paper. I found no source for that section.

The Biolandes process paragraph is a forum comment and I did not verify it.

"Orris grows in a fragrance" is also a forum comment. The mechanism I offer — a fatty phase needing time to disperse — is a guess, not a research result.

Jaeger measured β-ionone. Extending it to irone has no evidence. I include it because it is the only clean evidence in this molecular family, not because it applies to this material.

The 15% and 8% in the product names are strings in the database's supplier field, and I did not check with any manufacturer what those specifications mean — whether "15% irone" counts all irone isomers or one of them, I do not know.

References

M. Friščić, Ž. Maleš, I. Maleš, et al., Gas Chromatography-Mass Spectrometry Analysis of Volatile Organic Compounds from Three Endemic Iris Taxa: Headspace Solid-Phase Microextraction vs. Hydrodistillation, Molecules, 29(17), 4107 (2024). PMID 39274954. doi:10.3390/molecules29174107

S. R. Jaeger, J. F. McRae, C. M. Bava, et al., A Mendelian trait for olfactory sensitivity affects odor experience and food selection, Current Biology, 23(16), 1601-1605 (2013). PMID 23910657. doi:10.1016/j.cub.2013.07.030