Fixing Time — The Chemistry and Experience of Longevity in Natural Perfumery
When you work only with naturals, making a scent last becomes alchemy on two fronts: the nose and the lab. On one side you have visceral, instinctive impressions — what a material feels like on skin. On the other, you have measurable properties such as molecular weight, vapour pressure, and polarity that govern how fast those molecules diffuse.
Fixatives vs. Base Notes: The Basics
| Term | Primary Purpose | Typical Molecules | Perceptual Role |
|---|---|---|---|
| Base note | Provide depth & body; can also smell loud | High-MW sesquiterpenes, resins, woods | Forms the backbone of the perfume’s character |
| Fixative | Tether lighter volatiles so the whole lasts longer | Very low vapour-pressure resins, lactones, coumarins, macrocyclic musks | Often quiet or odourless; success is revealed over time |
A material can be both a base and a fixative (labdanum, vetiver), a base but poor fixative (galbanum), or a stealth fixative with hardly any smell at all (sclareol crystals from clary sage).
Fixatives in Perfumery
Now that we've distinguished fixatives from base notes, let’s explore the chemistry that makes them work—and why some naturals outperform others in longevity.
Fixatives are molecular anchors in perfumes, slowing the evaporation of volatile top/middle notes and enhancing longevity. They typically have high molecular weights (250–400 g/mol) and low vapor pressures, allowing them to linger on skin for hours. Below, we dissect key fixatives, their chemical foundations, and perfumery roles.
Vapour pressure describes how readily a molecule escapes into the air. The lower the number, the slower the evaporation and the longer it remains on skin. At 25 °C:
Citral (top-note aldehyde): ≈ 22 Pa → gone in minutes
Linalool (heart terpene alcohol): ≈ 0.2 Pa → hours
Ambrettolide (musk): ≈ 0.002 Pa → days
Fixatives work because they either have extremely low vapour pressure or interact with lighter molecules (via H-bonding, π-stacking), effectively lowering the mixture’s overall volatility. Vapour-pressure tables are practical tools: pair high-VP citruses with low-VP balsams if you need a natural eau de cologne to live past lunch.
Natural Fixative Ingredient Profiles: Descriptions & Observations
Each material includes a subjective impression followed by a breakdown and usage suggestions.
Ambrette Seed
Musky, nutty, with airy sweetness, slightly animalic.
This is often used as a musk substitute as it is one of the few natural ingredients that contain similar chemicals to the originally used Deer Musk glands. While its scent is hard to describe, there's a subtlety to it. It can be overwhelming in small amounts, covering the other ingredients in a mix. Almost slightly nutty. It is long-lasting. It does help to round out perfumes. I've found this to be too strong to have any "fixing" properties.
Chemistry: Contains ambrettolide (C₁₆H₂₈O₂), a macrocyclic lactone structurally akin to animalmusks.
Mechanism: Binds to olfactory receptors via hydrophobic interactions, mimicking deermusk’s tenacity.
Science: Studies show ambrette oil inhibits bacterial enzymes (e.g., TEM-72 β-lactamase), suggesting antimicrobial synergy in fragrances.
Practical Use: Use at ≤0.5% to avoid overpowering blends. Can help anchor florals.
Amyris
Resinous, smoky-tinges, balsamic, with dry wood undertones.
Softer support similar to frankincense, not sandalwood as it lacks the creamy sweetness. A lot of places recommend it as an alternative to Sandalwood, though it does not have many similarities and I do not believe it has any reason to be used as a Sandalwood replacement. Amyris is not sweet. While long-lasting, this tends to have a softer scent that does not compete with the perfume—similar in effect to frankincense when blended.
Chemistry: Rich in elemol (C₁₅H₂₆O) and valerianol (C₁₅H₂₆O), sesquiterpene alcohols.
Fixative Mechanism: Moderate fixative via hydrogen bonding.
Note: Amyris lacks santalol’s creamy depth but offers warmth in amber accords.
Angelica Root
Musky, earthy, with celery-like greenness, turpentine, coumarin, grassy.
Another natural musk alternative with complex green and musky layers.
Chemistry: Phthalides (e.g., ligustilide) and coumarin (C₉H₆O₂).
Fixative Mechanism: Coumarin’s crystalline structure stabilizes volatile aromatics.
Caution: Phototoxic furanocoumarins require dilution
Balsam of Peru
Vanilla-cinnamon-resin with leathery depth, piney, resinous, amber, woody, creamy.
Common allergen, yet widely used. Has a harsh edge yet fixes well. In my experiments, this is a successful extender of some ingredients, although the slightly harsh character of this may be difficult to blend.
Chemistry: Benzyl cinnamate (C₁₆H₁₄O₂) and vanillin (C₈H₈O₃).
Fixative Mechanism: High resin content forms a film that traps volatiles.
Allergen Alert: 30% of patch-test patients react to cinnamate derivatives.
Benzoin Resin
Vanilla-balsamic with powdered sugar sweetness, warm, amber, resinosus, cream soda.
Reminiscent of an older vanilla. It is not fresh, but it is warm. Adds warmth and a vintage tone to blends.
Chemistry: Benzoic acid (C₇H₆O₂) and coniferyl benzoate (C₁₇H₁₆O₄).
Fixative Mechanism: Resinous, non-volatile, physical entrapment properties, and likely Benzoin’s polar groups can engage in hydrogen bonding with alcohol-soluble notes, contributing to stabilization.
Uses: Extends caramelized notes.
Cedarwood
Dry pencil shavings (Virginia) vs. incense-like smoke (Atlas). Generally woody, balsamic, camphorous.
It’s hard to discuss cedarwood as there are so many varieties with completely different scent profiles. Generally, this is not a base note nor a fixative. The scent tends to be of cedar chips, woody, balsam, camphor. Varieties labeled as "cedarwood" can be derived from Junipers, Cypresses, Platycladus, Taiwania, Calocedrus, and Cedar of Lebanon. Many of these are not true cedars, and it can be confusing as to whether someone is referring to the Atlas Cedar, Virginia Cedar, or Cypress, which all have drastically different scent profiles.
Chemistry: Cedrol (C₁₅H₂₆O) in Juniperus virginiana; thujopsene (C₁₅H₂₄) in Atlas cedar.
Fixative Mechanism: Cedrol’s tricyclic structure slows evaporation. [Basically its a heavy molecule and its shape contributes to forces which enhances rigidity and likely resists evaporation]
Note: While true cedars (Cedrus spp.) are used in perfumery; many “cedar” oils are junipers.
Labdanum/Cistus
Animalic, honeyed, with ambergris-like warmth, musk, resin, sweet, animalic.
It is complex scent and can easily overpower most fragrances. Sweet and dirty, like an animal. Deep and tenacious. This is a somewhat successful fixative for other ingredients, although the strength of this scent is so powerful it eclipses others.
Chemistry: Labdanolic acid (C₂₀H₃₂O₂) and ambrox precursors.
Fixative Mechanism: heavy, non-volatile molecules
Clary Sage
Herbal, nutty, with a saline musk undertone, balsamic.
Overwhelming if over‑used. Has light floral notes.
Chemistry: Sclareol (C₂₀H₃₆O₂), a diterpene alcohol.
Fixative Mechanism: Clary sage’s linalool and linalyl acetate synergize with mid-notes like lavender, enhancing their longevity without overpowering them. Clary sage absolute and oil slow evaporation of top/middle notes via hydrogen bonding between sclareol’s hydroxyl groups and polar fragrance molecules. Acts as a “molecular net” in chypre and fougère perfumes, extending the lifespan of citrus, herbal, and amber notes.
Frankincense/Olibanum
Lemon-pine-copal, meditative, warm, balsamic, citrusy-resin.
Scent is long‑lasting but soft. The resin and essential oil do not have the same properties and do not smell the same. This is a somewhat successful fixative. It is a softer scent and easily masked; while long-lasting, it is not strong. Helps extend citrus notes.
Chemistry: α-Pinene (C₁₀H₁₆) and incensole acetate (C₂₂H₃₂O₄).
Fixative Mechanism: Moderate due to monoterpene volatility; resinoids > EOs for fixation. The EO generally will not have the same properties.
Types: The essential oil has none of the health benefits that have be researched from the resin. Better to buy Frankincense resin than Oil.
Galbanum
Crushed leaves, unripe tomato, and damp soil, sharp green, balsamic, woody.
One of the strongest ingredients; it quickly overpowers everything. Its behavior depends on the form, if you are using a resinoid or EO. Hard to work with, and I personally have not found that this is an effective fixative, but perhaps mileage varies.
Chemistry: β-Pinene (C₁₀H₁₆) and myrcene (C₁₀H₁₆).
Fixative: EO green top notes fade, but resinoid (30% sesquiterpenes) might act as a base fixative.
Immortelle/Helichrysum
Warm, honeyed, tea-like, with tobacco and liqueur undertones, lightly sweet, herbal, gently floral.
I would consider this a middle note. Have seen this classified as both a base note and heart note, but I haven't experienced it as a base not, maybe due to the extraction. Has no fixing properties in my experience.
Chemistry: Neryl acetate (≈42%): Floral-fruity ester; γ-Curcumene (≈18%): Sesquiterpene with spicy, woody facets, α-Pinene (≈25%): fresh pine-resin notes, Italidiones (β-diketones), Leathery, animalic nuances.
Low fixation capacity: Volatile monoterpenes (evaporate quickly, while sesquiterpenes linger but lack strong binding.
Role in perfumery: Adds warmth and complexity to chypres, ambers, and fougères but does not significantly extend longevity.
Myrrh
Warm, balsamic, slightly bitter.
Often paired with frankincense.
Your impression — Balsamic, warm resin; similar to frankincense. Balsamic, warm, resin. Similar to Frankincense and often used together.
Oakmoss
Damp forest floor, umami, earth, moss, wood, dark, decay, fungus.
A long lasting and improtant component of Fougère and Chypre style fragrances. Usually diluted to a lower concentration; frequently used with Vetiver. Smells like a walk in the woods. Long-lasting and strong in its profile.
Chemistry: Atranol (C₁₁H₁₀O₄) and chloroatranol (C₁₁H₉ClO₄).
Fixative Mechanism: Physical properties - it is heavy and non-volatile.
Regulation: EU restricts atranol to 0.1%
Opopanax (Sweet Myrrh)
Resinous, sweet, warm.
A softer cousin of myrrh.
Orris Root Butter
Floral, woody, violet-adjacent,
carrot seed, suede, delicate, gives powdery bloom;
Smells better in dilution. Frequently used as a modifier in perfumes. In my experiments, this is a somewhat successful fixative, although it creates a powdery effect and modifies the other ingredients rather strongly.
Chemistry: Irones (C₁₄H₂₂O), irones α/β/γ.
Fixative Mechanism: High MW (206 g/mol) and ketone polarity enhance tenacity.
Cost Factor: 1 kg orris butter requires 1 ton of rhizomes.
Note: A soft modifier more than a fixative. Adds powdery texture and atmosphere.
Patchouli
Wet earth, rich, dark chocolate, incense; aged dark grades fix, young grades overwhelm.
Easily overwhelming, very recognizable. Great in small amounts in gourmand additions. In my experiments, this is a somewhat successful fixative when aged and dark. The light and young version overpowers and smells a little clumsy in fixative concentrations.
Chemistry: Patchouli alcohol (C₁₅H₂₆O).
Fixative Mechanism: Aged patchouli oxidizes to norpatchoulenol, a smoother fixative.
Olfactory Profile: Notes: Patchouli that has been ages has a more robust and smooth scent profile.
Sandalwood
Creamy, woody, soft, milky, with pencil-wood nuances, sour, balsamic.
A warm, pleasant smell that can be used on its own or to modify/enhance other ingredients. In my experiments, this adds a round, smooth structure without stealing the spotlight and helps anchor volatiles. Sandalwood provides is a creamy roundness that is hard to notice unless you're familiar with it. It's not a strong scent on its own and is easily masked by others. Most folks are so accustomed to the synthetic forms that they are unfamiliar with what real sandalwood smells like. Like many oils, the best sandalwood is aged. Young sandalwood is sour and woody, less creamy.
In traditional Indian attars, sandalwood is both solvent and subtle base. Roses or jasmine are distilled into a sandalwood bath, and over months the heavier phenyl‑ethyl alcohols and indoles come to the fore. When worn, many attars open with glorious floral bloom while the sandalwood seems to “fade” under stronger molecules—proof that low vapour pressure alone does not guarantee perceptual prominence; odour impact and diffusion coefficients also decide what the nose registers.
Chemistry: α-Santalol (C₁₅H₂₄O) and β-santalol (C₁₅H₂₄O).
Fixative Mechanism: High molecular weight and low volatility.
Sustainability: Santalum album is vulnerable; Australian (S. spicatum) is considered eco-friendlier.
Storax/Liquidamber
Resinous, floral, balsamic, with a plastic topnote.
Precipitates in alcohol; this has strong notes of plastic that dissipate in some combinations but not all. Does not easily dilute in alcohol and is better blended into oil. With alcohol, there will be precipitate that should be filtered in the final composition. In my experiments, this is a somewhat successful fixative.
Details — Cinnamyl cinnamate & cinnamic acid (VP ≈ 0.015 Pa) supply leathery‑floral glue; 0.5–2 %.
Styrax: Cinnamyl cinnamate adds plastic-like depth (filter precipitates!).
Tolu Balsam
Amber, musk, sweet resin.
Often confused with Balsam of Peru
Vetiver
Earthy forest heaviness, smoky, rooty, with citrus peel brightness, woody, heavy.
A staple fixative and base note. Can be very harsh.
Chemistry: Vetiverol (C₁₅H₂₆O) and khusimone (C₁₅H₂₂O).
Fixative Mechanism: Physical properties slow down volatility.
Cultural Note: Haitian vetiver is grassier; Indonesian is smokier.
Vanilla
Warm, sweet, slightly woody, deep. Varies by region. Softens blends, however I suspect it is a weak fixative, if at all.
Vanilla: Vanillin (C₈H₈O₃)
Last updated May 2025 – this is a living document.
