Hot Throw vs Cold Throw
Hot throw and cold throw are two important measures used to evaluate the fragrance performance of scented candles. Understanding the difference between them helps candle makers optimize wax selection, fragrance load, wick size, curing time, and overall candle performance.
Cold Throw
Cold throw is the fragrance released by a candle when it is not burning. It is the scent perceived when opening the container, handling the candle, or smelling the candle at room temperature.
Cold throw is influenced by:
- Type and quality of fragrance oil
- Wax type and formulation
- Fragrance concentration
- Fragrance distribution within the wax
- Candle surface area
- Curing time
- Storage temperature and conditions
A strong cold throw can provide an attractive fragrance experience before the candle is lit, but it does not necessarily indicate that the candle will have an equally strong hot throw.
Hot Throw
Hot throw refers to the fragrance released by a candle while it is burning. As the wick heats the wax and creates a liquid melt pool, fragrance compounds are released into the surrounding air.
Hot throw is influenced by:
- Wick type and size
- Melt-pool temperature and size
- Wax formulation
- Fragrance type and concentration
- Candle diameter and container design
- Pouring and processing conditions
- Curing time
- Burning conditions and room size
Hot Throw vs Cold Throw
| Feature | Cold Throw | Hot Throw |
|---|---|---|
| Condition | Candle is unlit | Candle is burning |
| Fragrance source | Fragrance released from solid wax | Fragrance released from heated melt pool |
| Main factors | Wax, fragrance, concentration, curing | Wick, melt pool, wax, fragrance, curing |
| Evaluation | Smell the unlit candle | Evaluate fragrance during controlled burning |
| Primary purpose | Initial fragrance impression | Fragrance performance during use |
How to Improve Both
Achieving a good balance between hot and cold throw requires optimizing the entire candle formulation rather than simply increasing the fragrance load.
- Select a wax compatible with the chosen fragrance oil.
- Use an appropriate fragrance concentration within the wax supplier’s recommended limits.
- Mix fragrance thoroughly into the wax at the recommended temperature.
- Allow adequate curing time before evaluating performance.
- Select and test the correct wick for the candle diameter and wax formulation.
- Ensure the wick produces an appropriate melt pool without excessive flame size or soot.
- Conduct controlled burn tests to evaluate hot throw consistently.
- Store and test candles under consistent environmental conditions.
Importance of the Balance
A candle can have a strong cold throw but weak hot throw, or a relatively mild cold throw but excellent fragrance performance when burning. Therefore, both characteristics should be evaluated separately during product development.
The best candle formulations achieve a balance between fragrance strength, wax compatibility, wick performance, curing, and safe burning characteristics. Proper testing and formulation control help produce candles with a pleasant fragrance experience both before and during use.
