How Temperature Affects Essential Oils in Fragrance Oils

How Temperature Affects Essential Oils in Fragrance Oils for Candle Fragrance Oil

Overview: Why temperature matters for candle fragrance oil

Temperature directly influences volatility, solubility, viscosity, oxidation rate and physical stability of essential oils used in candle fragrance oil. Changes during storage, transport, formulation and burning alter both cold throw (scent from an unlit candle) and hot throw (scent when burning). Understanding these effects helps manufacturers and candle makers preserve fragrance integrity and deliver consistent scent performance to customers.

Volatility and scent release: cold throw vs hot throw

Essential oils contain many volatile compounds with a wide range of boiling points. At higher temperatures, more volatile molecules vaporize, increasing scent intensity (hot throw). At low temperatures, vapor pressure falls, reducing cold throw. For candle fragrance oil, that means a product stored or poured at inappropriate temperatures can show weak cold throw and unpredictable hot throw when burned.

Typical fragrance load and its temperature sensitivity

Different waxes accept different fragrance loads: typical guidance is 6–10% for common soy wax formulations and 6–12% for paraffin blends. Higher fragrance loads increase risk of volatility loss or phase separation under thermal stress. Always test fragrance load across expected temperature ranges rather than assuming lab performance equals real-world conditions.

Effect on mixing, pumping and production

Temperature controls viscosity. Cooler fragrance oils and essential-oil-rich blends can thicken or even partially crystallize, complicating pumping and homogeneous mixing into wax. Raising temperature modestly (10–30°C above room) lowers viscosity for easier handling, but excessive heat can drive off the most volatile scent notes. Most production lines find a balance by gently warming fragrance oil to 25–40°C for handling and adding to wax at the recommended pour temperature for the wax type.

Pour temperature: how and why it matters for candle fragrance oil

For good scent bind and consistent cold/hot throw, fragrance is added to molten wax at a specific temperature window. For many soy waxes, adding fragrance between 55–65°C is common; for paraffin-heavy systems the window can be 65–80°C. Too-high pour temperatures can accelerate evaporation of top notes and reduce overall scent strength; too-low temps can cause poor incorporation and separation. Always follow wax manufacturer recommendations and run controlled scent throw tests.

Oxidation, degradation and shelf life

Heat accelerates oxidation and other degradative reactions in essential oils. Typical shelf-life guidance: unopened fragrance oils often remain stable for 2–3 years when stored properly; essential oils vary — citrus oils commonly degrade faster (6–18 months) while woody/spicy oils can remain stable several years. Elevated storage or transit temperatures shorten these windows; keeping candle fragrance oil in stable, cool conditions preserves top notes and prevents off-notes from oxidation.

Physical changes at low temperatures

Cold can cause cloudiness, crystallization or phase separation in blends that include high levels of monoterpenes or stearoptenes (common in citrus essential oils). While freezing usually does not permanently ruin a fragrance, it can change appearance and pour behavior. Gentle reheating to 30–40°C with mixing typically restores clarity and homogeneity without damaging scent molecules.

High-temperature risks during storage and shipping

During summer shipping or storage near heat sources, fragrance oils can expand, leak or experience accelerated evaporation. Sustained temperatures above 40°C increase risk of container distortion and quality loss; above the flash point (check the product SDS) there are fire hazards. For candle fragrance oil, aim to avoid prolonged exposure to temperatures above 35–40°C during transit and warehousing.

Table: Temperature ranges, likely effects and recommended mitigation

Practical testing protocol for candle makers

To reliably measure temperature effects on candle fragrance oil, adopt a simple, repeatable test: use the same wax and wick, pour at recommended temperature with a defined fragrance load (e.g., 6% for soy), cure candles for 24–48 hours at 20–24°C, then evaluate cold throw in a controlled room. Burn tests at standard room temperature will assess hot throw. Repeat tests after subjecting fragrance oil to accelerated heat (e.g., 45°C for 1–2 weeks) to check for degradation.

Formulation adjustments to compensate for temperature effects

If a fragrance weakens after heat exposure, formulators can consider higher fragrance loads within safe, tested limits, or blending in higher-boiling base notes to preserve perceived strength. Antioxidants and stabilizers may be used in compliance with regulations to extend shelf life. However, altering formulae changes cost and may affect safety — always validate with stability and burn tests.

Packaging and storage best practices for manufacturers

Store candle fragrance oil in opaque or amber containers with tight seals to reduce light and air exposure. Maintain warehouse temperatures between 15–25°C where possible, and monitor humidity. For long-term storage, keep materials in original containers and implement inventory rotation. During shipping, use insulated packaging or temperature-controlled freight for sensitive or high-value blends when ambient temperatures may exceed recommended limits.

Handling unusual ingredients: citrus, aldehydes and naturals

Some essential oils like lemon, bergamot or other citrus are particularly sensitive to oxidation and photooxidation, producing off-notes over time. Aldehydic notes and natural extracts may also be more thermally unstable. When working with these components in candle fragrance oil, prioritize cooler storage, include antioxidants if appropriate, and shorten shelf time for opened batches.

Safety note: flash point and regulatory considerations

Always consult the Safety Data Sheet (SDS) and product technical data for flash point, flammability and handling instructions. Fragrance oils used in candle production are required to meet regulatory labeling and safety standards; temperature extremes that approach or exceed flash points create hazards. Maintain workplace controls and staff training on handling at elevated temperatures.

LEUXSCENT capability and how we help candle brands

LEUXSCENT, founded in 2003 and one of China's top-ten fragrance enterprises, offers tailored OEM/ODM solutions and R&D support for candle fragrance oil applications. With two production bases in Guangdong, 17 invention patents and technical centers, LEUXSCENT advises on optimal fragrance loads, pour temperatures and storage protocols to preserve essential oil integrity and ensure repeatable cold and hot throws across climates and supply chains.

Quick troubleshooting guide for common temperature-related issues

If candle fragrance oil appears cloudy after cold storage: warm to 30–40°C and mix. If scent has faded after shipping in heat: run comparative burn tests vs a fresh sample; consider reformulation or shorter storage times. If top notes are missing after production: check pour temperatures and reduce heat exposure in the production line.

FAQ — Temperature and Essential Oils in Candle Fragrance Oil

Q: What temperature should I store candle fragrance oil?

A: Aim for 15–25°C in a dark, dry place with airtight containers. Avoid extended storage above 35–40°C and protect from direct sunlight.

Q: Can fragrance oils freeze and will that ruin them?

A: Some oils may cloud or crystallize at low temperatures but gentle reheating to 30–40°C with mixing usually restores them. Freezing is not ideal but is not usually permanently damaging.

Q: At what temperature should I add fragrance to wax?

A: Follow your wax supplier's guidance: many soy waxes accept fragrance best at 55–65°C, while paraffin blends often take fragrance at 65–80°C. Avoid adding at very high temps that can evaporate volatile notes.

Q: How long do candle fragrance oils last?

A: Unopened fragrance oils commonly remain stable 2–3 years if stored properly. Essential-oil-heavy blends vary: citrus oils may degrade in 6–18 months, while woody/spicy oils can last several years. Test and rotate stock.

Q: Will heat during shipping affect my fragrance?

A: Yes. Prolonged heat (above 35–40°C) accelerates degradation and can cause leakage or off-odors. Use insulated packaging or temperature-controlled freight for sensitive shipments.

Q: How can I test whether temperature damaged a fragrance?

A: Perform side-by-side cold and hot throw tests using a control sample. Also check for visual changes, off-odors, and compare performance in burn tests after standard curing.

Q: Are there additives to stabilize essential oils against heat?

A: Antioxidants and stabilizers can slow oxidation; however, use only approved additives and validate their effect on scent and safety. The best approach is temperature control and careful formulation.