Candle wax is fundamentally a solid fuel source that requires heat to release its energy and fragrance. The moment a candle’s solid wax begins to turn into a liquid is defined by its melting point. This temperature is not a single fixed number but rather a range that varies significantly between different types of wax. Understanding this thermal characteristic is important because it dictates how a candle is made, how it burns, and how it must be stored.
The Melting Point Range of Common Waxes
The melting point is a defining physical property for any candle wax. Different chemical compositions result in widely varied melting ranges. Paraffin, the most commonly used wax derived from petroleum, has a broad melting range, typically from 115°F to 160°F (46°C to 71°C), depending on its grade and oil content. Lower melt-point paraffin is softer and often used for container candles, while higher melt-point grades are preferred for free-standing pillar candles.
Soy wax, a popular plant-based alternative, tends to have a lower melting point, generally falling between 110°F and 130°F (43°C to 54°C) for most container blends. This relatively low temperature contributes to a slower burn rate and a more efficient fragrance release, making it a favorite for scented candles. However, harder soy wax blends used for pillars may have a range extending up to 140°F (60°C).
Beeswax, a natural product created by honeybees, stands at the higher end of the spectrum, with a consistent melting point range of 144°F to 147°F (62°C to 64°C). This higher thermal stability makes it excellent for pillar and tapered candles that require a rigid structure. Coconut wax possesses a very low melting point, sometimes as low as 100°F (38°C), necessitating blending to increase firmness. Palm wax, by contrast, has a medium-high range, often melting between 130°F and 145°F (54°C and 63°C).
Factors Influencing Wax Hardness
The precise temperature at which a wax melts is directly linked to its underlying chemical structure. Waxes are composed primarily of long-chain hydrocarbons, and generally, the longer the carbon chain, the more energy is required to break the molecular bonds, resulting in a higher melting point. Paraffin wax, for example, is available in multiple grades because its refining process can isolate different chain lengths, allowing manufacturers to select a specific thermal profile.
For plant-based waxes, the process of hydrogenation is used to modify the melting point. Soybean oil is naturally liquid at room temperature, but full hydrogenation adds hydrogen atoms to the fatty acid chains, increasing their saturation and transforming the oil into the solid soy wax used for candles. This processing creates a wax with a crystalline structure that is solid at lower temperatures.
Manufacturers often use additives and blending to fine-tune the final melting temperature and hardness of a candle. Substances like stearic acid, a common additive, are mixed in to slightly raise the melting point and improve the wax’s opacity and firmness. Blending a low-melt wax, such as soy, with a small percentage of a high-melt wax, like beeswax or microcrystalline wax, is a common technique to achieve a desired performance characteristic, like a more stable container adhesion or a harder pillar structure.
Practical Effects of Temperature on Candles
The melting point of a candle has direct, practical implications for its use. Candles made with low-melt point waxes, such as many soy or coconut blends, are particularly susceptible to deformation if stored in a warm location, like a sunny window or a hot vehicle. This risk of bulk melting means that proper storage below the wax’s melting threshold is necessary to maintain the candle’s structural integrity.
Ambient heat can also cause a phenomenon known as “sweating,” where fragrance oils separate from the wax and bead up on the surface if the surrounding temperature approaches the wax’s melting point. This separation occurs because the wax softens and releases the oils, and is a common issue with lower-melting, highly scented waxes. It is important to distinguish this bulk melting from the functional melt pool created by the wick, which is designed to reach temperatures far exceeding the wax’s melting point to ensure the fuel is vaporized and burned.
Ignoring the melting point can create a safety hazard, particularly with free-standing pillar candles. If a candle is placed too close to a heat source, or if the ambient temperature is too high, the entire structure can soften and collapse, potentially causing the melted wax to spill and spread the flame. For this reason, candles with higher melting points are preferred for outdoor use or in warmer climates where structural stability is a concern.