Wax is a collective term for organic compounds that are malleable solids near ambient temperatures and become liquids above 45°C. These substances are characterized by their high molecular weight, non-polar nature, and water repellency. Waxes have a smooth, slightly greasy texture, making them useful in countless applications from protective coatings to cosmetics. The process of creating these materials varies dramatically depending on whether the source is a fossil fuel, an insect, or a plant.
Creating Wax from Crude Oil
The production of petroleum-based waxes, such as paraffin and microcrystalline wax, begins within the crude oil refining process. Crude oil is first subjected to fractional distillation, separating it into different fractions based on boiling points. The heavier lubricating oil fractions remaining after lighter products like gasoline and diesel are removed contain the waxy components, often referred to as “slack wax.”
Solvent dewaxing separates the wax from the lubricating oil. This involves mixing the slack wax with a solvent, such as methyl ethyl ketone, and chilling the mixture. As the temperature drops, wax molecules crystallize and precipitate out of the solution while the oil remains liquid. The crystallized wax is then physically separated from the solvent-oil mixture through filtration or centrifugation, leaving a semi-refined wax. Further purification often requires “sweating,” where the wax is slowly heated to drain oil pockets, or hydrotreating, which uses hydrogen and a catalyst to remove impurities and improve stability.
Harvesting and Refining Animal Waxes
Waxes derived from animals, most notably beeswax, are collected and purified using physical methods. Beeswax is naturally secreted by worker honeybees to build the honeycomb structure used for rearing young and storing honey. The wax is collected by separating it from the honey and the rest of the hive structure.
Raw honeycomb is typically melted using hot water or steam, which liquefies the wax while leaving behind heavier impurities and honey residue. The melted wax is then strained through a mesh or cloth to remove foreign material, such as cocoon fragments. A subsequent clarification step involves allowing the melted wax to cool slowly, enabling any remaining fine particles to settle by gravity. The purified wax is then cooled rapidly to solidify it into blocks for commercial processing.
Processing Plant-Based Waxes
Processing plant-based waxes involves either chemical modification or physical harvesting, depending on the botanical source. For soy wax, the process begins by extracting oil from cleaned, de-hulled, and flaked soybeans. This soybean oil, which is naturally liquid, is then subjected to hydrogenation.
Hydrogenation involves reacting the oil with hydrogen gas at high temperatures and pressure using a nickel catalyst. This process converts the unsaturated fatty acids in the oil into saturated ones, which raises the oil’s melting point. The result is a solid, malleable wax at room temperature. Harder botanical waxes, like carnauba wax, are obtained through physical methods. The wax is scraped or beaten off the surface of dried palm leaves, and the resulting powder is often melted and filtered to remove plant debris.
Purification and Commercial Blending
Raw waxes often possess a distinct color and odor, requiring purification steps before commercial use. These are removed through processes like bleaching and deodorizing. Bleaching can be achieved using chemical agents or through clay treatment, where the wax is mixed with activated clay to adsorb color-causing impurities.
Deodorizing involves treating the wax with steam or vacuum distillation to strip away volatile compounds that contribute to unwanted smells. The final stage involves blending different waxes to achieve desired performance characteristics, such as hardness, flexibility, or fragrance retention. For example, a softer wax may be blended with a harder microcrystalline wax to increase rigidity. Commercial additives, including dyes and fragrance oils, are incorporated at this stage, completing the transformation into a finished product.