Waxes are a diverse group of organic compounds. They are typically solid at room temperature, becoming liquid with low viscosity when heated. Waxes are also characterized by their water-repellent nature, meaning they are largely insoluble in water. This class of materials is primarily composed of hydrocarbons, organic compounds made of hydrogen and carbon atoms. These characteristics allow waxes to be used across many applications, from cosmetics to industrial coatings.
Waxes from Nature
Waxes derived from natural sources originate from either plants or animals, representing complex mixtures of organic compounds. Beeswax, for instance, is produced by worker honeybees from specialized glands on their abdomen. This natural wax is primarily composed of esters of fatty acids and long-chain alcohols, contributing to its malleability and water-repellent qualities. Beeswax contains over 300 components, many contributing to its distinctive honey-like scent.
Plant-based waxes include carnauba wax, often called “Brazil wax.” This hard, yellowish wax is exuded from the leaves of the carnauba palm, native to northeastern Brazil, as a protective coating. Carnauba wax is mainly composed of aliphatic esters, diesters of 4-hydroxycinnamic acid, and fatty alcohols, giving it a high melting point and a glossy finish. Candelilla wax is another plant-derived wax, sourced from the leaves of the candelilla shrub found in northern Mexico and the southwestern United States. This hard, brittle, yellowish-brown wax primarily consists of hydrocarbons, resins, and esters derived from fatty acids and alcohols.
Lanolin, also known as wool wax, originates from the sebaceous glands of wool-bearing animals, particularly sheep. It is a blend of lipids, primarily long-chain waxy esters or sterol esters. Lanolin’s composition provides waterproofing properties, helping sheep shed water from their coats and offering emollient benefits in human skin care products. It is obtained by purifying wool grease extracted from sheep’s wool.
Waxes from Petroleum
Petroleum refining yields waxes, primarily composed of hydrocarbons. Paraffin wax is a soft, colorless solid obtained by de-oiling slack wax, a byproduct of lubricating oil refining from crude oil. Its chemical structure consists mainly of straight-chain alkane hydrocarbon molecules (20-40 carbon atoms). Paraffin wax is characterized by its low melting point (46-68°C) and its brittle nature.
Microcrystalline wax is another petroleum-derived wax, produced from de-oiling petrolatum or heavy lubricating oil fractions. Unlike paraffin wax, microcrystalline wax contains a higher percentage of branched and cyclic hydrocarbons, giving it a finer crystal structure. This molecular difference results in microcrystalline wax being more flexible, elastic, and viscous than paraffin wax, often with a higher melting point.
Petrolatum, commonly known as petroleum jelly, is a semi-solid mixture of hydrocarbons also obtained during petroleum refining. It is derived from the de-oiling of paraffinic residual oil and primarily consists of saturated hydrocarbons (carbon numbers often >25). Petrolatum is recognized for its hydrophobic nature and emollient properties, making it widely used in cosmetic and pharmaceutical applications. Its semi-solid state at room temperature distinguishes it, while its melting point typically falls between 40-70°C.
Man-Made Waxes
Beyond natural and petroleum sources, waxes are also synthetically produced to meet specific industrial needs. These man-made waxes are engineered polymers designed to mimic or enhance the properties of their natural counterparts. Polyethylene waxes are created by polymerizing ethylene gas. Their composition involves saturated hydrocarbons with varying molecular weights, tailored for specific applications. Polyethylene waxes are valued for their high melting points, low viscosity, and excellent water repellency.
Fischer-Tropsch waxes represent another class of synthetic waxes, produced through the Fischer-Tropsch process. This chemical synthesis converts carbon monoxide and hydrogen into hydrocarbons using a catalyst. These waxes consist primarily of unbranched, linear saturated hydrocarbon chains, offering high purity and consistent properties. Fischer-Tropsch waxes exhibit a high melting point and superior thermal stability, making them suitable for applications requiring enhanced heat resistance. These waxes allow for precise control over their molecular structure and characteristics, providing consistent performance for various industrial processes.