Using Fragrance Oils in Candles: Usage Rates, Flashpoint and Getting a Strong Throw

A guide to the fragrance side of candle making — how much to use, when to add it, and how to fix the problems that come down to the oil rather than the wax.

There’s no shortage of guides explaining how to melt wax and centre a wick. This isn’t one of them. This is about the ingredient we actually specialise in — the fragrance oils — because in our experience that’s where most candle problems start, and it’s the part that’s hardest to find good information about in New Zealand.

We publish the technical data for every fragrance we sell — usage rates, IFRA limits, flashpoint, vanillin content — on each product page. This guide explains what those numbers mean and how to use them.

How much fragrance should you use?

Start at 8%, and work within 6–12%.

That range covers almost every container candle. Below 6% you’ll usually struggle for hot throw. Above 12% you’re past what most waxes can hold, and the excess doesn’t make the candle stronger — it just has nowhere to go.

The upper limit isn’t ours to set, though. It’s your wax’s. Every wax has a maximum fragrance load, and it varies. Golden Wax 464 — the most popular container soy in New Zealand — is generally specified to around 10%. Other soys and coconut blends differ, some taking more and some considerably less. Check your wax manufacturer’s specification and treat that as your ceiling, not our 12%.

Calculating it

Fragrance percentage is by weight of wax, not by volume, and not by total finished weight.

Fragrance (g) = wax weight (g) × fragrance %

So for 500g of wax at 8%:

500 × 0.08 = 40g of fragrance oil

A digital scale accurate to 0.1g matters here. Small differences in fragrance load make a real difference to throw, and measuring oil by volume introduces error because fragrance oils vary in density.

Why more isn’t better

Overloading is one of the most common mistakes we see, and it’s an easy one to make — if 8% smells good, surely 12% smells better?

It doesn’t. Once the wax is saturated, the surplus oil separates out. That’s what causes sweating (beads of oil on the surface) and seeping (oil pooling around the wick or at the base). Worse, excess oil can affect how the candle burns — fragrance oil is fuel, and a candle carrying more of it than the wick was sized for can burn hotter than intended.

If a fragrance seems weak, the answer is almost never more oil. It’s usually cure time or wick size.

IFRA limits: the bit most guides skip

IFRA limits for fragrance oils in candle making: the bit most guides skip

Every fragrance oil has an IFRA certificate specifying maximum safe usage rates by application. Candles fall under IFRA Category 12.

This matters because IFRA limits are set per fragrance, not per category of product. Some of our fragrances are safe well above 12% in a candle; others are restricted below the level you’d assume. The limit is driven by the individual materials in the blend, so there’s no way to guess it from the scent.

We publish the IFRA category maximums on every product page. Where the IFRA limit is lower than your wax’s fragrance load, the IFRA limit wins.

If you sell your candles, this isn’t optional. It’s the standard the industry works to, and it’s what a compliance-minded stockist or market organiser will expect you to be able to evidence.

To read more about IFRA guidelines, visit IFRA https://ifrafragrance.org/

Flashpoint: what it actually means

Flashpoint is the temperature at which a fragrance oil’s vapours can ignite in the presence of an ignition source. Every fragrance we sell has its flashpoint published on the product page.

Two things people commonly get wrong about it:

It is not the temperature at which fragrance “burns off”. This is the most persistent myth in candle making. Adding fragrance to wax above its flashpoint does not evaporate the scent or destroy your throw. The fragrance is dissolved into the wax, and the wax is nowhere near hot enough to cause the oil to flash in an open container without an ignition source.

It does matter for shipping and storage. Flashpoint determines how a fragrance is classified for transport, which is why some oils have shipping restrictions. It’s also why you should never heat fragrance oil directly, and never leave it near an open flame or heat source.

So: don’t use flashpoint to decide your adding temperature. Use it to handle and store the oil sensibly.

When to add fragrance

Add fragrance at around 80–85°C, and stir for a full two minutes.

The stirring matters more than most people think. Fragrance needs to be properly dispersed through the wax to bind evenly — a quick swirl leaves pockets of concentrated oil, which show up later as uneven throw or surface defects.

Adding too cool is a more common problem than adding too hot. If the wax has started to thicken, the fragrance won’t disperse properly no matter how long you stir.

Then let it cool to your wax’s recommended pour temperature before pouring.

Cure time

Two weeks for soy. One week is the practical minimum; two is where most fragrances reach their best.

Curing is the fragrance binding into the wax structure. It isn’t the same as hardening — a candle is solid within a few hours and nowhere near ready. Burn it at 24 hours and you’ll get a weak hot throw and conclude the fragrance is no good, when it simply hadn’t finished.

Rough guide by wax:

Wax	Cure time
Soy	1–2 weeks, 2 preferred
Coconut and coconut blends	1–2 weeks
Paraffin	2–3 days
Beeswax	1–2 days

Some heavy fragrances — vanillas, musks, ambers — keep improving past two weeks. If you’re testing a complex scent, it’s worth a burn at two weeks and another at four.

Cure at room temperature, out of direct sunlight, with the lids off or loosely placed. Sealing them airtight while curing can trap moisture.

Troubleshooting the fragrance problems

Weak hot throw

The most common complaint, and usually not the fragrance’s fault.

Work through it in this order:

Cure time. Under a week is the single most likely cause. Wait, then retest.
Wick size. Too small a wick can’t form a full melt pool, and a candle that doesn’t melt to the edges can’t release scent from the whole surface. This is the second most common cause and the one people least expect.
Fragrance load. If you’re at 6%, try 8–10%. But check your wax’s maximum first.
Room size. A 200g candle won’t scent an open-plan living area. This is physics, not a fault.
The fragrance itself. Some scent families are naturally quieter — delicate florals and light citrus throw less powerfully than gourmands and heavy ambers. Nothing is wrong; they’re just softer.

Sweating or seeping oil

Almost always fragrance load above what the wax can hold. Reduce the percentage. Temperature swings during cooling can also bring it on, so avoid curing somewhere that gets warm during the day.

Discolouration

Wax discolouration appears as candles that yellows, browns or tans over time. It isn’t a defect, it doesn’t affect how the candle performs, and in most cases it can’t be prevented — only anticipated. There are several causes:

Vanillin. The best known and most predictable. It’s the compound behind vanilla, caramel, bakery and many amber fragrances, and it oxidises to brown over time. The higher the vanillin content, the faster and darker the shift. We publish vanillin content on our product pages, so this one you can check before you buy.

The oil’s own colour. Some fragrance oils are naturally amber, gold or deep brown, and they tint the wax the moment you add them. This shows immediately rather than developing over weeks, so it’s easy to distinguish from oxidation.

Citrus and other terpene-rich oils. Cold-pressed citrus — lemon, orange, bergamot, lime — contains terpenes that oxidise readily on exposure to air and light. In a candle this typically shows as gradual yellowing. It’s the same chemistry that makes citrus oils go off faster than other materials in storage.

Spice materials. Cinnamon, clove and related fragrances contain compounds such as cinnamaldehyde and eugenol that darken over time, independently of any vanillin.

Light. Regardless of fragrance, UV exposure yellows wax. A candle sitting in a sunny window will discolour faster than one in a cupboard.

If you want your candles to stay white, start with a 0% vanillin fragrance, avoid heavy citrus and spice, and store finished stock out of direct sunlight. If you’re using a fragrance that will inevitably shift, colouring the wax deliberately is often the better answer — a cream or amber candle that darkens slightly looks intentional in a way a browning white one doesn’t.

You can find all our vanillin free fragrances here.

Frosting and wet spots

Neither is caused by fragrance.

Frosting — the white crystalline bloom on soy — is natural vegetable wax crystallising. Purely cosmetic. Pour temperature adjustments can reduce it; nothing eliminates it entirely.

Wet spots — where wax pulls away from the glass — are an adhesion issue caused by cooling. Warming your jars before pouring and cooling more slowly helps.

Both come up constantly in fragrance troubleshooting discussions, so they’re worth knowing about, but changing your fragrance won’t fix either.

A note on testing

Everything above is a starting point. Your wax, your jars, your wick and your climate all interact, and the only way to know how a fragrance performs in your system is to make a test candle.

Test one variable at a time, label everything with the date and the exact percentage, and burn under the conditions your customers actually will — full 3–4 hour burns, not five-minute checks.

That data is a sound starting point, but it isn’t a substitute for testing in your own setup. A small test batch before committing to a production run will always be worth the fortnight it costs you.