What Temperature to Add Fragrance Oil to Candle Wax

Temperature is one of the quieter reasons a candle turns out well or badly. Add fragrance oil too cool and it may not bind fully with the wax. Pour too hot or too cold and you can get wet spots, rough tops or sinkholes. The good news is that you do not need to guess: your wax supplier has already tested this.

The usual answer: around 185°F (85°C)

Many container soy waxes and blends are commonly scented at around 185°F (85°C). At that temperature the wax is fully liquid and thin enough for fragrance oil to disperse evenly with gentle stirring.

That number is a common guideline, not a universal rule. Some waxes recommend adding fragrance a little lower, some a little higher. Paraffin, coconut blends and specialty waxes each have their own instructions. The technical data sheet for your exact wax is the reference to follow, and it usually lists three temperatures:

1. Melt temperature, the temperature to heat the wax to
2. Fragrance addition temperature, when to add the oil
3. Pour temperature, when to pour into containers

Why temperature matters when adding fragrance

Fragrance oil and wax need to combine thoroughly. When the wax is hot and fluid, the oil spreads through it easily. If the wax has cooled and thickened, the oil may not disperse evenly. The result can be:

• oil pooling on top of the set candle
• uneven scent from one candle to the next in the same batch
• a weaker hot throw than the fragrance load suggests

Adding at the recommended temperature and stirring properly avoids most of these problems.

How long to stir

Stir gently and steadily for about two minutes after adding the oil. Many makers find this is the step they rush most.

• Stir slowly so you don't whip air into the wax, which can cause bubbles and rough tops.
• Scrape the sides and bottom of the pitcher as you go.
• Keep stirring even after the oil looks mixed in. Some oils look combined before they truly are.

What about flash point?

Flash point causes more worry than it deserves. A fragrance oil's flash point is the lowest temperature at which its vapor can ignite briefly when an ignition source is present. It is used mainly to classify the oil for safe shipping and storage.

Flash point is not the temperature at which the fragrance "burns off" or stops working. Many fragrance oils have flash points below 185°F and are routinely added at that temperature without problems. Fragrance and candle suppliers generally advise following the wax's recommended addition temperature rather than adjusting it to the flash point.

That said, flash point is still a safety number. Keep hot oil and wax away from open flames and heat sources, never leave melting wax unattended, and heat wax with a double boiler or a dedicated melter rather than directly on a burner.

Pour temperature

After you add and mix the fragrance, you usually let the wax cool to its pour temperature. For many soy container waxes this is somewhere around 120 to 140°F (49 to 60°C), but it varies a lot between waxes.

Pour temperature affects the look of the candle more than the scent:

• Too hot can increase shrinkage, sinkholes and frosting in soy wax.
• Too cool can leave rough tops, jump lines and poor glass adhesion, which shows up as wet spots.

If you get wet spots or rough tops, adjust your pour temperature in small steps of about 5°F and keep notes.

Warming your containers

Cold jars cool the wax at the edges quickly. In a cold room this can cause poor adhesion and wet spots. Many makers warm jars slightly before pouring with a heat gun or a warm oven at a low setting. The goal is warm, not hot.

A simple temperature routine

1. Melt the wax to the supplier's melt temperature.
2. Let it cool or hold it at the fragrance addition temperature.
3. Weigh the fragrance oil while the wax melts, using the fragrance oil calculator for the amount.
4. Add the oil and stir gently for about two minutes.
5. Add dye, if using, and stir again.
6. Cool to pour temperature and pour into warm, clean containers.
7. Let the candles set undisturbed at room temperature, away from drafts.

A good thermometer makes all of this repeatable. An instant-read probe thermometer is accurate and easy to clean; infrared thermometers measure surface temperature only and can mislead you in a pitcher of liquid wax.

Frequently asked questions

Can I add fragrance oil at a lower temperature?

You can if your wax supplier recommends it, but going much below their guidance risks poor binding and oil seeping out later. When testing, change only one variable at a time.

Does adding fragrance too hot weaken the scent?

There is no strong evidence that briefly adding fragrance at the wax's recommended temperature weakens a candle. Holding the wax very hot for long periods is a different matter, so add the oil, stir and move on.

Why do I need a thermometer if the wax looks melted?

Wax that looks fully melted can still be well below the addition temperature. A thermometer removes the guesswork and makes batches consistent.