Candles & Wax Melts: Fragrance Load, Hot/Cold Throw, Paraffin vs Soy

A candle is a silent vessel that carries fragrance oil. Liquid candle fragrance is released when the wax melts and locked in when it solidifies. The secret lies in striking the right balance between these two states. Let's first establish what fragrance load means.

Fragrance load is the amount of candle fragrance oil added relative to the total weight of the wax. The typical range is 6–10%. However, this figure is not a fixed rule — it depends on how much fragrance oil the wax base can actually hold (its oil-binding capacity). Any fragrance that exceeds the base's capacity will seep to the surface, form oil pools, and clog the wick.

Here is a critical point: longevity and scent strength are not determined by load percentage alone. The real deciding factor is the volatility of the molecules within the fragrance oil. A citrus-heavy fragrance may dissipate quickly even at 10% load, while a amber-, musk-, or resin-dominant composition can hold a room for hours at just 7%.

A candle's scent speaks at two distinct moments — its quiet, unlit state on the shelf, and its lively state under a flame. These two behave independently of each other.

Cold throw is the scent a candle emits at room temperature, without being lit. It is the fragrance of the display and the moment of sale. Hot throw is the scent that diffuses into the room as the flame heats the melt pool — it is the performance that matters during use.

Many makers are delighted by a strong cold throw, only to be disappointed by the hot throw. This is because volatile top notes (citrus, aldehydes) come forward when the candle is cold but rapidly evaporate and disappear when heat is applied. For strong hot-throw performance, choose fragrance oils weighted towards the heart and base.

The wax base determines from the outset how a fragrance oil will behave. Every wax has a different oil-binding capacity, melting point, and scent-release curve. Choosing the right base comes before finding the right ratio.

Paraffin holds fragrance generously and delivers powerful hot throw, which is why it remains prevalent in the industry. Soy wax has a lower melting point and is easier to work with; it appeals to the "natural" market segment but doesn't diffuse fragrance as aggressively as paraffin and can develop whitish frosting on the surface. Blend and coconut-based waxes attempt to balance the advantages of both.

Let's correct a common misconception here: soy is not automatically safer simply because it is "natural." Safety depends not on the source of the base, but on the molecular composition of the added fragrance oil and its IFRA compliance. Both soy and paraffin burn cleanly when paired with the correct wick and the correct load.

We build the formula using grams (g) because volume (ml) can be misleading. The specific gravity of fragrance oils varies across a wide range: citrus oils are approximately 0.84 g/ml, while heavy resins and some synthetics exceed 1.10 g/ml. If you measure by ml alone, you will end up with too much or too little. Always work by weight.

A wax melt (scented wax tablet) is wickless — it melts on a warmer and releases its fragrance. Because there is no combustion, the heat is lower, which allows the fragrance to diffuse more slowly but more cleanly.

Fragrance loads in wax melts are generally kept slightly higher than in candles — in the 8–12% range — since there is no risk of wick clogging. A small amount of paraffin or a hardener is added to a soy base to provide firmness; otherwise the tablet will collapse on the warmer. Even so, determine the oil-binding limit of your base through testing — an excessive load will cause surface seepage.

The logic of candle scenting is related to other application areas. In rinse-off products the fragrance usage rate is lower — the category differences covered in the Fragrance in Soap and Fragrance in Personal Care articles will be useful here. For enclosed, heat-driven environments, the ventilation principles discussed in the Car Air Fresheners article operate on similar logic.