Carrier Oils Compared: DPG, IPM, Ethanol and Their Effect on Throw
Two suppliers quote you the same fragrance concentrate, but one delivers it in dipropylene glycol and the other in isopropyl myristate, and the finished products do not smell or behave alike even though the oil is nominally identical. The c
Two suppliers quote you the same fragrance concentrate, but one delivers it in dipropylene glycol and the other in isopropyl myristate, and the finished products do not smell or behave alike even though the oil is nominally identical. The carrier is not packaging filler; it is part of the formula, and it decides how fast the fragrance leaves the surface and how it feels on skin.
This article compares the three carriers you will most often meet in fragrance oils — DPG, IPM and ethanol — and explains how each one changes evaporation, solubility, flash point and perceived throw. It gives you the criteria for choosing a carrier by application and a test sequence you can run before you lock a ratio into a specification.
Table of Contents
- What a carrier actually does
- DPG: the default diluent
- IPM: slower, oilier, skin-friendly
- Ethanol: fast evaporation, high throw
- How the carrier shapes throw over time
- Choosing a carrier by application
- Practical guide: selecting a carrier for a new fragrance product
- Frequently asked questions
- Conclusion
What a carrier actually does
A carrier is the solvent that dilutes a fragrance concentrate so it can be dispensed, blended and dosed. It performs three jobs at once: it dissolves the concentrate into a stable single phase, it lowers the cost and the intensity to a usable level, and it controls the rate at which the volatile aroma molecules evaporate into the air.
Solubility comes first
Before you judge a carrier by throw, confirm it holds the concentrate in a clear, stable solution without clouding or separating at room temperature and, for products that ship in winter, at low temperature. A carrier that throws beautifully but drops the concentrate out of solution is useless in production.
DPG: the default diluent
Dipropylene glycol is the workhorse carrier for fragrance oils because it is a good general solvent, low in odour, and mild enough for many skin and home applications. It evaporates slowly, which stretches the life of a product but also softens the initial burst of scent.
Evaporation profile
DPG lingers on a surface for a long time, so a fragrance in DPG reads as flatter at first but steadier over hours. For a reed diffuser or a scented card this can be an advantage; for a product that needs a sharp first impression it can feel muted unless the concentrate is rebalanced upward in the top notes.
IPM: slower, oilier, skin-friendly
Isopropyl myristate is an ester with a heavier, oilier feel. It evaporates even more slowly than DPG and is often chosen for leave-on skin products because it spreads smoothly and acts as an emollient rather than a thin, drying solvent.
When IPM is the wrong choice
The same oiliness that helps a body oil can leave a visible film on glass or a candle jar, and it can slow the wicking of a reed diffuser. IPM is a deliberate trade-off: better skin feel and longer life, at the cost of a weaker opening and a heavier residue.
Ethanol: fast evaporation, high throw
Ethanol is the opposite end of the spectrum. It evaporates within minutes, releasing the fragrance in a sharp, bright burst, which is why fine fragrance and room sprays are built on it. The same speed makes it short-lived and flammable, so it belongs in products designed for a quick release, not in a slow ambient diffuser.
Flash point and handling
Ethanol has a low flash point, which changes storage, filling and shipping requirements compared with a DPG or IPM base. If you are choosing a carrier for a product that will be filled on a line with heat sources or shipped as a liquid, the flash point is a hard constraint before it is a quality question.
How the carrier shapes throw over time
Throw is not a single number; it is a curve that rises and falls as the volatile molecules leave the surface. The carrier sets the shape of that curve by slowing or speeding the evaporation of everything dissolved in it.
Top notes leave first regardless
Light citrus and green molecules evaporate faster than the heavier woods and musks in the same blend. A fast carrier amplifies this difference, making the opening bright but the drydown thin, while a slow carrier compresses the difference and reads as more even but less exciting.
Vapour pressure is the mechanism
Each molecule has a vapour pressure that measures how readily it leaves a liquid at a given temperature. A carrier lowers the effective evaporation rate of the blend by dilution and by intermolecular interaction, so the same concentrate can sit at the top of the throw curve for minutes in ethanol or for hours in IPM.
| Note type | Volatility | Carrier that suits it |
|---|---|---|
| Top notes | High, leaves first | Ethanol for a bright burst |
| Heart notes | Moderate | DPG for steady release |
| Base notes | Low, lingers | IPM for slow, long release |
Choosing a carrier by application
The right carrier follows the product's release window. A quick-release spray wants ethanol, an all-day body oil wants IPM, and a steady ambient product wants DPG or a glycol blend between the two.
| Carrier | Evaporation | Feel and residue | Best fit |
|---|---|---|---|
| DPG | Slow, steady | Thin, low residue | Reed diffusers, scented cards, general oils |
| IPM | Very slow | Oily, emollient film | Body oils, leave-on skin products |
| Ethanol | Fast, bright | None, drying | Fine fragrance, room sprays |
Practical guide: selecting a carrier for a new fragrance product
Step 1 — Define the release window
Write down how long the product should smell and how sharp the opening should be. A one-hour room spray and an eight-week diffuser demand different carriers before you even look at solubility.
Step 2 — Test concentrate solubility
Blend the concentrate into each candidate carrier and watch for clouding or separation at room temperature and in a chilled sample. Reject any carrier that does not hold a clear, stable solution.
Step 3 — Set the evaporation budget
Weigh a sample over time in your target conditions and record the mass loss curve. This tells you whether the carrier delivers the lifespan the product promises.
Step 4 — Screen flash point and compliance
Confirm the flash point and any market restrictions for the carrier and the finished blend before committing, and treat the current official text as the authority.
Step 5 — Run a side-by-side throw comparison
Prepare the same concentrate in each candidate carrier and have a small panel score opening, mid and drydown. The difference in perception is often larger than the chemistry suggests.
Step 6 — Lock the ratio in the spec
Record the chosen carrier and its ratio by weight in the specification so every future batch reproduces the throw curve you approved.
Frequently asked questions
What is a fragrance carrier?
A fragrance carrier is the solvent that dilutes a concentrate into a usable, dosable liquid. It dissolves the concentrate, controls evaporation and determines how the product feels and how long it smells.
What is DPG in fragrance oil?
DPG, or dipropylene glycol, is a low-odour glycol solvent widely used as the default diluent in fragrance oils. It evaporates slowly and gives a steady, long-lasting release with little residue.
What is IPM?
IPM, or isopropyl myristate, is a fatty ester used as a carrier where an oily, emollient feel is wanted. It evaporates very slowly and is common in body oils and leave-on skin products.
Does DPG reduce throw?
DPG softens the opening burst because it evaporates slowly, but it extends the overall life of the scent. Whether that is a reduction depends on your target: a bright first impression suffers, while long ambient performance improves.
Can I use ethanol in a reed diffuser?
Ethanol is generally unsuitable for a reed diffuser because it evaporates too fast, empties the base quickly and delivers a short, intense burst rather than weeks of steady scent. A glycol or blended base is the usual choice.
Why does IPM feel oily on skin?
IPM is an ester with a heavier, emollient character, so it leaves a smooth film rather than drying down to nothing. That film is a feature in body oils and a drawback on surfaces where residue is unwanted.
How much carrier is typical in a fragrance oil?
The ratio varies widely with the concentrate strength and the product. A concentrate may be diluted anywhere from a light cut to a heavy one, so confirm the exact ratio by weight with the supplier rather than assuming a standard.
Does the carrier change a fragrance's regulatory classification?
It can, because the carrier is part of the finished blend and may carry its own restrictions or flash-point implications. Confirm the current official text for the relevant market rather than relying on a general rule.
Conclusion
The carrier is the second half of the formula, and choosing it changes the product as much as the concentrate does. DPG gives a steady default, IPM trades brightness for skin feel and longevity, and ethanol buys a bright burst at the cost of lifespan and flammability.
Match the carrier to the release window, confirm solubility and flash point, then lock the ratio into the specification. For a carrier decision made with your application and market in mind, review how we build fragrance oil packs or ask about custom formulation, and see the fragrance oils we manufacture.
Discuss your fragrance programme with our team:
WhatsApp: +86 17324762943
Email: adon@customperfumeoem.com
Website: customperfumeoem.com
