Iso E Super Longevity: Why Escentric Molecules Lasts 8-16 Hours (The Ghost Molecule)

"Why does Escentric Molecules Molecule 01 last 8-16 hours when it barely smells like anything?"

And more importantly: "Why can I smell it intensely while my friend smells nothing?"

Welcome to Iso E Super - perfumery's ghost molecule.

It has a molecular weight of 234 and a vapor pressure so low (0.001735 mmHg) that it persists on skin for 8-16 hours and on fabric for over a week. It creates a mysterious "halo effect" where the scent seems to emanate from your skin rather than sit on top of it.

But here's the twist: 20-25% of people have specific anosmia - a genetic inability to smell Iso E Super at all. You could be wearing pure Molecule 01, and 1 in 4 people won't detect anything.

Meanwhile, others smell a powerful woody-velvety presence.

In this post, I'll explain what Iso E Super is, why it lasts so long, the science behind the anosmia mystery, and why it's become a cult molecule in modern perfumery.

Quick Answer: Iso E Super Longevity Chart

On fabric/smelling strip: 172+ hours (7+ days)

Comparison to other molecules:

Key takeaway: Iso E Super lasts 4-8x longer than linalool, 16-32x longer than limonene. Similar longevity to ambroxan and sandalwood.

What Is Iso E Super?

Iso E Super is a synthetic woody-amber molecule created to mimic the dry, velvety facets of cedarwood and ambergris.

Full chemical name: 1-(1,2,3,4,5,6,7,8-Octahydro-2,3,8,8-tetramethyl-2-naphthyl)ethanone (OTNE)

Molecular weight: 234.38 g/mol

Chemical formula: C₁₆H₂₆O

CAS Number: 54464-57-2

Structure: Bicyclic ketone with a naphthyl ring system

Smell profile:

• Woody, cedar-like, velvety
• Dry, slightly amber, musky
• Smooth, subtle, skin-like
• Abstract, hard to describe

The NTP Technical Report describes it as having "a woody, slightly ambergris odour, reminiscent of clean human skin, and its odour is long-lasting on skin and fabric."

Discovery:

• Invented in 1973 by John B. Hall and James M. Sanders at IFF (International Flavors & Fragrances)
• Originally patented as "Isocyclemone E"
• Synthesized via Diels-Alder reaction between myrcene and methyl pentenone

Isomer composition:

• 30-65% β-isomer (primary)
• 10-26% α-isomer
• 8-20% γ-isomer

Different isomers have slightly different smell profiles, creating complexity.

Trade names:

• Iso E Super (IFF - original)
• Amberfleur
• Orbitone
• Anthamber
• Patchouli Ethanone

Annual production: 5,000-22,000 metric tons (massive volume)

Why Iso E Super Lasts 8-16 Hours

Three chemical properties give Iso E Super exceptional longevity:

1. High Molecular Weight: 234

At 234, Iso E Super is firmly in base note territory:

Iso E Super (234) sits alongside ambroxan (236) and sandalwood (220) in the persistent base note range.

2. Extremely Low Vapor Pressure: 0.001735 mmHg

Technical data shows Iso E Super vapor pressure at 20°C is 0.001735 mmHg.

Comparison:

Lower vapor pressure = molecules stay in liquid phase = much slower evaporation.

Iso E Super has one of the lowest vapor pressures of common perfume molecules.

3. Low Water Solubility, High Alcohol Solubility

Iso E Super is:

• Water solubility: 0.00268 g/L (nearly insoluble in water)
• Highly soluble in alcohol (perfume base)

This means:

• Sweat/humidity doesn't wash it away
• Stays dissolved in fragrance formulation
• Binds to skin oils effectively
• Resists environmental degradation

Result: 172+ hours on smelling strips (7+ days of detectable scent).

On skin, the combination of binding to oils + low vapor pressure gives 8-16 hour longevity.

The Anosmia Mystery: Why 20-25% Can't Smell It

Here's where Iso E Super gets weird.

20-25% of people have specific anosmia to Iso E Super - they literally cannot smell it.

Research from Givaudan and RIFM indicates this is one of the highest anosmia rates for any common perfume molecule.

What Is Specific Anosmia?

Specific anosmia is defined as "the inability to perceive a specific odor while olfactory perception is otherwise intact."

You can smell roses, citrus, vanilla - everything except Iso E Super.

Why it happens:

Smell perception requires:

1. Molecule binds to olfactory receptor
2. Receptor sends signal to brain
3. Brain interprets as "smell"

If you have a genetic variant in the Iso E Super receptor, step 1 fails. No binding = no signal = no smell.

The Vanish-and-Reappear Phenomenon

Even people who CAN smell Iso E Super experience something strange: it seems to vanish and reappear.

What happens:

• You spray Molecule 01
• Strong woody smell for 5-10 minutes
• Smell disappears completely (olfactory fatigue)
• 20-30 minutes later, it's back
• This cycle repeats for hours

Escentric Molecules explains: The molecule binds and unbinds to olfactory receptors, creating a "now you smell it, now you don't" effect.

Why this matters:

If you test Iso E Super-heavy perfumes in a store:

• First spray: Might smell amazing
• 5 minutes later: Smells like nothing
• You think: "This has no longevity"
• Wrong: Your nose adapted. Others still smell it. It's still there.

This is why Iso E Super is called the "ghost molecule."

Individual Variation

Even among people who CAN smell it, perception varies wildly:

Person A: "Strong, powerful, woody-velvety, lasts all day" Person B: "Subtle skin scent, barely there, intimate" Person C: "Can't smell anything"

Same perfume. Same concentration. Completely different experiences.

Practical implication:

Blind-buying Iso E Super-heavy perfumes (Dior Fahrenheit, Molecule 01, many Tom Fords) is risky. You might have anosmia and waste money on something you can't smell.

Always test on skin first.

The Halo Effect: How Iso E Super Creates Radiance

Iso E Super doesn't just last long. It creates a unique halo effect.

What Is the Halo Effect?

When used at high concentrations (20-70%), Iso E Super:

• Makes fragrance appear to emanate FROM skin (not sit ON skin)
• Creates spatial "aura" around the wearer
• Enhances perception of surrounding notes
• Projects more than the concentration suggests

How it works:

Iso E Super has unique diffusion properties:

• Evaporates very slowly (low vapor pressure)
• But what DOES evaporate creates strong projection
• Creates a "cloud" effect rather than directional trail
• Interacts with skin chemistry uniquely

Perfumer Geza Schoen (creator of Molecule 01) discovered: "The common denominator in all the fragrances I liked was that they contained a large dose of it."

He realized Iso E Super at 30-70% concentrations created an addictive, mysterious quality.

Famous Example: Dior Fahrenheit

Dior Fahrenheit (1988) contains an estimated 25-30% Iso E Super - revolutionary for its time.

The result:

• Massive projection (legendary sillage)
• 8-12 hour longevity
• Mysterious "What are you wearing?" quality
• Cult following for 35+ years

Without Iso E Super, Fahrenheit would be a standard woody-leather fragrance. With it, it's an icon.

Escentric Molecules Molecule 01: The Iso E Super Experiment

In 2006, perfumer Geza Schoen did something radical: 100% pure Iso E Super.

No other ingredients. Just the molecule.

The Concept

"Molecule 01" is:

• 65% Iso E Super in alcohol
• No top notes
• No heart notes
• No other base notes
• Pure Iso E Super

The pitch: It interacts with YOUR skin chemistry to create a unique scent for each person.

The reality: Due to anosmia and individual variation, it smells completely different (or invisible) to different people.

Why It Became a Cult Hit

Traditional perfumery: Perfume smells the same on everyone (mostly) Molecule 01: Smells different on everyone (or not at all)

People love it because:

• Mysterious: "What IS that smell?"
• Exclusive: Not everyone can smell it
• Personal: Smells different on each person
• Long-lasting: 8-16 hours easily
• Intimate: Skin-scent quality

Critics say: It's just Iso E Super. You can buy that for $50/kg. Why pay $125 for 100ml?

Fans say: The concept, the experience, the mystery. It's not about the molecule - it's about what it represents.

Famous Perfumes with Iso E Super

Iso E Super is everywhere in modern perfumery:

1. Dior Fahrenheit (1988)

• Estimated 25-30% Iso E Super
• Pioneered high-concentration use
• Woody-leather with violet and gasoline facets

2. Escentric Molecules Molecule 01 (2006)

• 65% Iso E Super (rest is alcohol)
• Pure molecule experience
• Cult following

3. Tom Ford Oud Wood (2007)

• Significant Iso E Super (estimated 15-20%)
• Creates smooth, velvety oud
• Radiance effect

4. Terre d'Hermès (2006)

• Moderate Iso E Super (10-15%)
• Enhances woody-mineral character
• Contributes to longevity

5. Many Tom Ford fragrances

• Tom Ford loves Iso E Super
• Used in varying concentrations
• Creates signature "Tom Ford smoothness"

Other notable uses:

• Incenza (Lorenzo Villoresi) - woody-spicy
• Not a Perfume (Juliette Has a Gun) - similar to Molecule 01
• Numerous modern woody/aromatic fragrances

Iso E Super has become so ubiquitous that it's hard to find modern woody perfumes WITHOUT it.

India Climate Performance

How does Iso E Super perform in Indian heat?

Results:

Key insight: Iso E Super maintains good longevity even in heat (5-10 hours at 35°C).

Compared to other molecules:

• Limonene at 35°C: 20-40 min
• Linalool at 35°C: 1.5-3 hours
• Iso E Super at 35°C: 5-10 hours ✓

While it does evaporate faster in heat, the baseline vapor pressure is so low that it still lasts most of the day.

Practical implication:

Iso E Super-heavy perfumes work well in Indian climate:

• Dior Fahrenheit: 6-10 hours in Mumbai summer
• Molecule 01: 5-8 hours in Delhi heat
• Tom Ford Oud Wood: 8-12 hours (oud + Iso E Super combo)

Not as exceptional as in cooler climates, but still very good.

How to Maximize Iso E Super Longevity

Iso E Super already lasts 8-16 hours, but to push it further:

1. Apply to Fabric (Not Just Skin)

Iso E Super lasts 172+ hours on fabric - over a week!

Best fabrics:

• Cotton shirts/t-shirts
• Wool scarves
• Jacket collars
• Hair (if alcohol doesn't bother you)

Why fabric is better: No skin oils to absorb it, no body heat to evaporate it. Pure slow-release diffusion.

2. Layer with Complementary Woods

Iso E Super works beautifully with:

• Cedarwood (natural amplification)
• Sandalwood (creamy + velvety)
• Vetiver (earthy + smooth)
• Patchouli (woody + musky)

Layering creates depth and extends the overall composition.

3. Test for Anosmia First

Before buying Iso E Super-heavy perfumes:

• Spray on wrist
• Wait 10 minutes
• Ask someone else: "Can you smell this?"
• If they can and you can't → you have anosmia

Save yourself money. Don't buy perfumes you can't smell.

4. Proper Storage

Safety studies show Iso E Super is stable, but optimal storage:

• Cool, dark place (15-25°C)
• Keep sealed (minimize air exposure)
• Original box (blocks light)
• Use within 3-5 years

Iso E Super is quite stable (boiling point 290°C), but proper storage extends life.

Safety and IFRA Standards

Iso E Super is safe for use in perfumery.

Safety Profile

Comprehensive toxicology review concluded: "ACK materials [including Iso E Super] do not present a safety concern at current levels of use as fragrance ingredients."

Toxicity: Low (oral LD50 >5 g/kg) Sensitization: Low potential Phototoxicity: None Environmental: Biodegradable

IFRA Standards:

• Allowed in all fragrance categories
• Typical use: 5-15% (EDT), 10-20% (EDP), 15-40% (Parfum)
• Escentric Molecules uses 65% (well within safe range)

Population tolerance:

• 75-80% can smell it normally (safe, pleasant)
• 20-25% have anosmia (genetic, not a safety issue)

Iso E Super has been used since 1973 with excellent safety record.

House of Sultan and Iso E Super

We don't use Iso E Super in our formulations. We prefer natural woody base notes.

Why?

Transparency: Our customers value knowing exactly what's in their perfumes. Natural sandalwood, oud, and patchouli are more transparent than synthetic molecules.

Anosmia risk: 20-25% of people can't smell Iso E Super. We don't want 1 in 4 customers unable to appreciate our perfumes.

Natural complexity: Sandalwood oil (santalol) has more depth and complexity than Iso E Super's smooth velvety character.

Heritage: We're rooted in traditional Indian perfumery (attars, oud, sandalwood). Iso E Super is a modern Western creation.

Rustam Formulation

Base notes:

• Sandalwood oil (santalol): 12-24hr longevity, creamy woody character
• Oud oil: 8-12hr longevity, resinous depth
• Patchouli: 10-18hr longevity, earthy richness

No Iso E Super, yet Rustam achieves 24+ hour longevity through natural base notes.

Full breakdown: Rustam Molecular Profile

Key Takeaways

Iso E Super longevity:

• ✓ 8-16 hours at 25°C
• ✓ 5-10 hours at 35°C (Indian summer)
• ✓ 172+ hours on fabric (7+ days)

Why it lasts so long:

• High molecular weight (234 - base note)
• Extremely low vapor pressure (0.001735 mmHg)
• Low water solubility (resists washing away)
• Binds to skin oils effectively

The anosmia mystery:

• 20-25% have specific anosmia (can't smell it)
• Vanish-and-reappear phenomenon (even for those who can)
• Wildly different perceptions among individuals
• Genetic OR variation causes anosmia

Unique properties:

• Halo effect (emanates from skin)
• Radiance at high concentrations (20-70%)
• "Ghost molecule" behavior
• Skin-scent intimate quality

Famous perfumes:

• Dior Fahrenheit (25-30%)
• Escentric Molecules Molecule 01 (65%)
• Tom Ford fragrances (various)
• Terre d'Hermès (moderate use)

For perfume shopping:

• ALWAYS test before buying
• Ask others if they smell it (anosmia check)
• Expect 8-16hr longevity if you CAN smell it
• Works well even in Indian heat (5-10hr)

Bottom line: Iso E Super is perfumery's most mysterious molecule - exceptional longevity, creates mesmerizing halo effects, but 1 in 4 people can't smell it at all. Test before you buy.

Further Reading

Want to understand longevity of other molecules?

• Perfume Molecule Longevity Chart: Complete MW Guide - Master reference hub
• Ambroxan Longevity: Why Dior Sauvage Lasts 8-12 Hours - Similar base note performance
• Galaxolide Longevity: Synthetic Musk Excellence - Long-lasting musk comparison
• Cashmeran Longevity: The Velvety Woody Musk - Created by same chemist
• Oud Molecule Breakdown: Natural vs Synthetic - Complex base note analysis
• 11 Fascinating Fragrance Chemistry Facts - Surprising discoveries

Looking for perfumes with natural base notes instead of synthetics? Browse our collection →

About Syed Asif Sultan

Founder of House of Sultan. Passionate about fragrance chemistry and transparency in perfumery.