Soy wax is a plant-based material that serves as a natural alternative to traditional paraffin wax. This vegetable wax is derived directly from the oil of the common soybean, offering a clean-burning and renewable source for various products. While it has found utility in cosmetic and industrial applications, its primary use is in the manufacturing of container candles and wax melts. Understanding how this substance is created requires examining its origin, beginning with its agricultural source and following its transformation through industrial processes.
The Primary Raw Material Source
The journey of soy wax begins with the soybean plant, a legume cultivated globally. Soybeans are one of the world’s most significant agricultural commodities, grown predominantly for their oil and high-protein meal.
Global cultivation is heavily concentrated in a few key regions. Brazil, the United States, and Argentina collectively account for approximately 80% of the world’s total soybean output. The harvested beans contain roughly 18% to 22% oil by weight, which is the specific component later processed into the final wax product.
Extracting the Crude Oil
Once harvested, the soybeans undergo several preparation steps before the oil can be separated from the rest of the bean structure. First, the beans are thoroughly cleaned to remove dirt and foreign material, then cracked and dehulled to strip away the tough outer shell. The remaining inner portion is then rolled into thin flakes, which maximizes the surface area for oil extraction.
The crude liquid oil is typically extracted from these flakes using one of two methods: mechanical pressing or solvent extraction. Mechanical pressing, or expeller pressing, involves crushing the flakes to physically squeeze out the oil. Solvent extraction is more efficient for large-scale production, where a solvent like commercial hexane is used to dissolve the oil from the flakes. After the oil is separated, the solvent is carefully removed from the crude oil through evaporation and recovery processes. The resulting crude soybean oil is a liquid, ready for the next stage of chemical modification.
Transforming Oil into Wax
The liquid soybean oil must undergo hydrogenation to convert it into the solid wax form. This process involves reacting the oil with hydrogen gas at high temperatures, typically between 140°C and 225°C, and in the presence of a nickel catalyst. Soybean oil is naturally composed of unsaturated fatty acids, meaning its chemical structure contains double bonds that make it liquid at room temperature.
The addition of hydrogen across these double bonds converts the unsaturated fatty acids into saturated fatty acids, increasing the molecule’s stability. This change in chemical structure significantly raises the oil’s melting point, causing it to solidify into a wax-like consistency. The degree of saturation can be precisely controlled, allowing manufacturers to produce waxes with different textures and hardness. Partial hydrogenation yields a softer wax, ideal for container candles, while fuller hydrogenation creates a firmer wax that can be used for pillar candles. The final product is then filtered and refined to remove the nickel catalyst and any remaining impurities.