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The scent is faint when unlit and intensifies after lighting—this precisely demonstrates the candle's excellent fragrance-locking technology, a key indicator of its quality. The underlying principle involves physics and chemistry, which
can be understood using a vivid analogy:
Imagine a scented candle as a "fragrance reservoir."
· The wax itself acts as the reservoir's dam, locking in the water (fragrance molecules).
· When unlit (cold smell): Just like a reservoir without releasing water, only a very small amount of water (fragrance molecules) can escape through natural evaporation (evaporation), so the scent is faint.
· After lighting (hot smell): Just like heating the reservoir, opening the sluice gate. Heat is the driving force for fragrance release, causing a large amount of water (fragrance molecules) to rush out, thus intensifying the scent.
Below, we explain this process in detail from a scientific perspective:
1. Why is the scent faint when unlit? (Cold Scent)
• Fragrance is "locked" in solid wax: High-quality scented candles use excellent fragrance-locking technology to evenly encapsulate and fix fragrance molecules within the crystalline structure of the wax. Since wax itself is solid, its molecular movement is slow, effectively preventing the fragrance from evaporating rapidly and in large quantities into the air at room temperature.
• Slow evaporation at room temperature: The "cold scent" you can smell represents only a very small portion of the fragrance molecules that have escaped the wax's confinement and successfully evaporated into the air. If a candle has a
very strong fragrance even before it's lit, it may indicate:
• Poor fragrance-locking technology: The wax body hasn't effectively locked in the fragrance, causing it to continue to evaporate in large quantities at room temperature. This not only shortens the candle's lifespan but may also mean that the fragrance dissipates quickly after lighting.
• The use of inferior fragrance with excessive volatility.
Therefore, an excellent scented candle should have an elegant, subtle, and layered fragrance when cold-smelled, rather than being "flashy" and "pungent." 2. Why does the scent intensify after lighting? (Hot Smell)
When a candle is lit, two key processes occur simultaneously, releasing the fragrance:
• Process 1: Melting of Wax and Release of Fragrance
• The heat of the candle melts the wax around the wick, forming a pool of molten wax.
• The solid wax transforms into liquid wax, its molecular structure loosening. The fragrance molecules, previously locked within, are released and dissolved in the liquid wax pool.
• Process 2: Capillary Action and Heat Diffusion
• The liquid, fragrance-rich wax is drawn up to the flame through capillary action from the wick.
• At the high temperature of the flame, these fragrance molecules gain extremely high energy, rapidly vaporizing and diffusing into the surrounding air.
• This process is continuous and efficient: the candle flame continuously melts the wax -> fragrance is released -> liquid wax is drawn up -> fragrance vaporizes and diffuses due to heat.
This is the direct source of your strong fragrance – the vaporized fragrance oil.
An important comparison: Why do some low-quality candles have no scent after lighting? If a candle has a very faint scent after lighting, or has a waxy or unpleasant odor, it usually means:
1. Poor quality or low proportion of fragrance oil: The fragrance itself is insufficient.
2. Failed fragrance-locking process: The temperature during manufacturing may be too high, causing a large amount of fragrance oil to evaporate or chemically denature during the injection stage, and the fragrance has been "burned away."
3. Incompatibility between wax and fragrance oil: The fragrance oil cannot be effectively contained and released.
4. Wick problem: The wick is too small or made of the wrong material, resulting in insufficient heat to form a sufficiently large wax pool to release the fragrance.
In short, in unlit (cold smell) candles, the fragrance oil is physically locked in by the solid wax crystal structure and relies solely on natural evaporation. The scent is faint, elegant, and subtle, which is a sign of a good fragrance-locking process.
When lit (and smelled warm), the heat melts the wax, releasing fragrance, which is then vaporized and diffused through the capillary action of the wick. The scent intensifies, becoming fuller and longer-lasting – this indicates the fragrance
has been effectively released.
Therefore, the situation you experience – "faint when unlit, strong when lit" – is a normal and ideal characteristic of a properly made, high-quality scented candle.
