Synthetic fragrance oils: how to use one legally and what it does to a balm

Reading an IFRA certificate, use at 0.2 to 2 percent by category, vanillin discolouration, flashpoints and the allergen declaration a fragrance oil still triggers.

A fragrance oil is a compounded blend of aroma chemicals sold with a use limit attached. That limit is the whole point of the material: unlike an essential oil, whose composition you inherit from a plant, a fragrance compound arrives with a certificate telling you the maximum percentage permitted in each product category. Getting the certificate right is most of the work. The rest is what the compound does to a wax base once it is in there, which is not nothing.

• INCI: Parfum (EU) or Fragrance (US)
• Lip products are Category 1
• Body balm 0.5-2%
• Add below 50-60 C
• Allergen declaration still applies

What is actually in the bottle

A fragrance oil has two parts. The compound is a blend of twenty to two hundred aroma chemicals, drawn from synthetic materials, natural isolates and sometimes whole essential oils. The diluent is a solvent that carries it, standardises its strength and makes it pourable, and is often 20 to 80% of what you buy.

The diluent decides whether the fragrance behaves in an anhydrous base. Dipropylene glycol is the industry default because it is cheap, odourless and stable, and it is a poor fit for a balm: polar, only sparingly miscible with triglycerides and waxes, and at 2% it can leave a balm faintly cloudy or weeping droplets a fortnight later. Isopropyl myristate, benzyl benzoate, triethyl citrate and medium chain triglycerides are oil compatible and cause none of that. Ask which one you are getting before you buy a kilogram; the principle is in solubility in anhydrous formulas.

On an ingredient list the whole thing appears as one word, Parfum in the EU or Fragrance in the US, followed by any declarable allergens. That single word is why fragrance oils are cheaper to label than essential oils and why they tell a buyer so little. The trade-off against botanical materials is worked through in essential oils versus fragrance oils.

The IFRA certificate, line by line

An IFRA conformity certificate is issued by the compounder for a specific fragrance, because IFRA Standards restrict individual aroma chemicals by product category. The compounder knows the confidential formula and converts it into one number you can use.

Read it in this order.

1. Check the amendment. The 51st Amendment is the current set of Standards, published in 2023, and its compliance dates for both new and existing compounds have passed. A certificate written against the 49th or 50th Amendment is out of date and needs reissuing.
2. Check the date and identity. It should name the fragrance and a code matching your invoice. A generic certificate covering a supplier's whole range is not a certificate.
3. Find your category row. The certificate lists all twelve IFRA categories with a maximum percentage in the finished consumer product for each. Read the row for what you are making, not the highest number on the page.
4. Read what the blank means. A dash, "not supported" or "0.00%" in your category is a prohibition for that use, not an absence of data. Category 1 is blank on a great many fragrance oils.
5. Note that IFRA is not the only limit. The Standards are an industry commitment. EU Annexes II and III are law and run alongside them, and where they disagree the tighter figure governs. See selling balms in the UK and EU.

Two rows catch people out. Facial and beard products sit in 5B, tighter than the 5A row people default to, so a beard balm and a body balm are not interchangeable. And a cleansing balm meant to be emulsified and rinsed sits in Category 9, usually far looser than anything leave-on.

How much to use, and why the range is wide

Three separate ceilings apply and you take the lowest: the IFRA figure for your category, the level at which the scent is pleasant rather than aggressive, and the level at which the balm still sets. The second binds most often in body products, the first in lip products.

Scale matters more than the percentage looks. At 1% a 60 g test batch takes 0.6 g, which a 0.01 g scale handles. At 0.3% a 30 g batch takes 0.09 g, which most bench scales cannot resolve, so scale the batch up or make a 10% predilution in a carrier oil. Do not count drops: fragrance oil drop mass varies from roughly 20 to 40 mg with viscosity and dropper bore.

Lips are the hard case

Category 1 is the strictest of the twelve because a lip product is partly eaten. Two things follow. The permitted percentage for a given compound is typically five to fifty times lower than its Category 5A figure, and Category 1 carries an extra requirement that almost no craft source mentions: the materials must also be recognised as safe as flavouring ingredients under the IOFI Code of Practice. A compound can be a perfectly good body fragrance and fail that test outright, which is why the Category 1 row is blank so often.

This is where the flavour oil and fragrance oil distinction becomes practical rather than semantic. A flavour oil is compounded from materials assessed for ingestion and supplied for taste; a fragrance oil is compounded to IFRA and supplied for smell. They overlap in composition but not in the paperwork behind them, and rates and solubility are covered in lip balm flavour and sweeteners.

Before you put any scent in a lip product, get four things from the supplier: an IFRA certificate with a numeric Category 1 figure, a written statement that the material is intended for lip application, confirmation that the diluent is oil soluble and not propylene glycol or ethanol, and the allergen statement. If any of the four is missing, the answer is no. The equivalent constraint on botanical materials, where the limits bind per constituent rather than per compound, is set out in essential oils in balms.

Vanillin, ethyl vanillin and the browning problem

Any vanilla, caramel, bakery, tonka or amber fragrance contains vanillin or ethyl vanillin, and both discolour. Vanillin is a phenolic aldehyde: it oxidises and condenses into coloured polyphenolic products, a reaction driven by oxygen, light, heat and traces of metal. Ethyl vanillin is stronger as a scent and browns harder. The result is a balm that starts ivory and goes tan, then coffee, over weeks to months, worst at the exposed surface of an open tin.

The working threshold quoted across the fragrance trade is about 1% vanillin content in the fragrance compound. Below that, discolouration is usually slow enough to be irrelevant within a normal shelf life. Above it, expect visible browning in a pale base, and the effect scales with both the vanillin content and your use level.

Vanillin browning is a colour change, not spoilage, and it is not the same reaction as rancidity. A customer cannot tell the two apart, which is the commercial problem. If you sell a vanilla balm, say on the label that darkening is expected.

Flashpoint, addition temperature and what heat costs you

Every fragrance data sheet carries a flashpoint, the lowest temperature at which the material gives off enough vapour to ignite in the presence of a source, measured closed cup. Most fragrance oils fall between 60 and 100 C. Citrus-heavy and aldehyde-rich compounds can sit between 40 and 60 C, and anything at or below 60 C is a Class 3 flammable liquid for transport under the UN Model Regulations, which is why some suppliers will not post it by air.

In a workshop the flashpoint tells you where to store the bottle, away from hobs and heat guns, and gives a rough guide to volatility. It does not mean a balm will ignite, because a water bath has no ignition source and cannot exceed 100 C. The real cost of a hot addition is scent, not fire. Top notes are the most volatile components by definition, so adding fragrance to a 75 C melt boils off the citrus and green notes preferentially and leaves the base notes behind. The batch does not smell weaker so much as different, and usually duller. Add off the heat, below 50 to 60 C, immediately before pouring, stirring gently to avoid whipping in air. Those windows sit inside the general framework in pour temperatures, and the longer-term version of the same complaint is covered in scent fades in balm.

What a fragrance oil does to the wax network

Fragrance is a low viscosity liquid added to a structured oleogel, and at 1 to 2% it is not inert.

• Softening

  The balm sets softer than the control

  Aroma chemicals act as solvents in the oil phase and interfere with wax crystal growth, described in oleogels and wax networks. A useful workshop rule of thumb is half a point to one point of extra wax per 2% fragrance, confirmed by a hardness check against an unfragranced control rather than assumed.

• Clouding and weeping

  Haze, beads or a damp film

  Almost always a polar diluent that will not dissolve in the base. It appears as haze on cooling or as droplets at the surface after one to three weeks, and no amount of stirring fixes it. Diagnosed in balm separated in layers.

• Packaging attack

  Crazed tubes, lifted labels

  Fragrance components craze polystyrene, soften some polypropylene closures and dissolve label adhesives and inks. Glass, aluminium, PET and HDPE are safe. Check the material against packaging compatibility before you fill.

Seizing, the sudden thickening soap and candle makers describe, is not really a balm fault. What gets reported as seizing in a wax base is usually fragrance added into a melt that had already begun to set, trapping crystal and leaving grain, or a diluent separating on contact. Both are avoided by adding into a fully clear melt brought down to temperature, not one on its way back up.

The allergen declaration a fragrance oil still triggers

Nothing about a synthetic compound exempts it from allergen labelling. Linalool made in a reactor declares exactly as linalool distilled from lavender, and compounders use large quantities of both. Ask for the allergen statement at the same time as the IFRA certificate, and check that it was written against the annex as amended in 2023 rather than the older 26-substance list.

The arithmetic is a single multiplication: the allergen's percentage of the compound, multiplied by your use level, compared against 0.001% for a leave-on balm or 0.01% for a rinse-off one. A compound containing 4% limonene, used at 1%, puts limonene at 0.04% of the product, forty times the threshold, so it goes on the label. Worked examples and the full list are in fragrance allergens.

The advantage over botanical materials is narrower than it sounds. A compounder can build to a low-allergen brief, which no distiller can do. What you cannot get is a citrus, lavender or rose character with nothing declarable, because the molecules that produce those characters are the listed ones. The United States has no equivalent duty and "Fragrance" alone suffices; see labelling cosmetics in the US.

Phthalate free, IFRA compliant, nature identical

Three phrases appear on nearly every fragrance oil listing and each means less than it looks.

Phthalate free in practice means free of diethyl phthalate, which was widely used as a fragrance diluent and fixative. The phthalates with the serious toxicological record, including DBP, DEHP and BBP, are already prohibited in EU cosmetics under Annex II, so no compliant fragrance sold for cosmetic use in Europe contains them. The claim is therefore about DEP specifically, and DEP remains legal in cosmetics in the EU and the US. It is a preference, not a safety upgrade, and calling it one edges into the territory covered in chemical free and clean beauty claims.

IFRA compliant without an amendment number and a category figure is a slogan. Compliance is category specific, so a compound can be entirely compliant in Category 5A and prohibited in Category 1 at the same time. Ask which amendment and which category.

Nature identical describes a molecule synthesised in a reactor that is chemically indistinguishable from one found in a plant, such as vanillin, linalool or geraniol. It has no regulatory definition in EU cosmetics law, and the natural content standards go the other way: under ISO 16128 and the main organic certification schemes, a nature-identical material counts as synthetic. It also makes no difference to skin, since a nature-identical allergen is still an allergen and still declares. What certification schemes will and will not accept is set out in natural and organic certifications.

Testing a new fragrance before you commit

Fragrance is the ingredient most likely to fail in month three rather than on the bench, so it earns its own trial. A single 60 g melt split three ways gives you almost everything.

1. Make a control. Pour a third of the batch with no fragrance. Every later judgement about colour and hardness is a comparison against it, and without one you will argue with yourself.
2. Dose at your intended level and at twice it. The double lets you see the failure mode early. If the 2x sample browns, weeps or softens, the 1x sample will do the same more slowly.
3. Fill the real packaging. Including the closure and the label, because both are part of the test. Fill at least one unit of each material you plan to sell in.
4. Store three ways for eight weeks. Ambient dark, 40 C, and a bright windowsill. Held at 40 C, the browning and weeping you would otherwise see in half a year show up inside two months; the interpretation and its limits are in accelerated ageing.
5. Score at week 0, 2, 4 and 8. Colour against the control, surface weeping, hardness by thumb or penetrometer, scent character and strength, and any change to tube, tin or label. Write the results into the batch file as you go, with the date and the storage condition against each score.

Approving a fragrance on the strength of how the pot smelled on pouring day is the single most common reason a small line ends up with a stock of brown, weeping tins it cannot sell.

When a fragrance oil is the right answer, and when it is not

Choose a fragrance oil when you need a scent that is reproducible batch to batch, cheap per unit, available in characters no plant produces, and covered by a document that states your maximum use level outright. For a repeatable commercial line those advantages are decisive, and a compounder can control allergen load and stability in ways a distiller cannot. Do not use one where the certificate does not support the category, which most often means lip products, and do not use one at all in a balm for infants, for broken or inflamed skin, or in anything sold on the basis of being minimal. Fragrance contributes nothing to occlusion, emolliency or barrier function.

Two limits sit under everything above. IFRA Standards are revised in amendments and EU annexes change one regulation at a time, so every figure here is a snapshot and the certificate for the material in front of you governs. And nothing here is a safety assessment: in the EU and UK a qualified assessor signs off the finished product, not the ingredient, and can reach a lower number than the certificate does. The browning, softening and packaging effects are workshop patterns rather than measured constants, which is why the eight week trial is not optional. For the exception where high loads are the point, see solid perfume.

Reviewed and updated 6 September 2026. Spotted an error? Tell us and we will fix and log it.