Micro-crystalline waxes are a type of wax produced by de-oiling petrolatum, as part of the petroleum refining process. In contrast to the more familiar paraffin wax which contains mostly unbranched alkanes, micro crystalline wax contains a higher percentage of iso paraffinic (branched) hydrocarbons and naphthenic hydrocarbons. It is characterized by the fineness of its crystals in contrast to the larger crystal of paraffin wax. It consists of high molecular weight saturated aliphatic hydrocarbons. It is generally darker, more viscous, denser, tackier and more elastic than paraffin waxes, and has a higher molecular weight and melting point.
he elastic and adhesive characteristics of microcrystalline waxes are related to the non-straight chain components which they contain. Typical micro crystalline wax crystal structure is small and thin, making them more flexible than paraffin wax. It is commonly used in cosmetic formulations. Micro-crystalline waxes when produced by wax refiners are typically produced to meet a number of ASTM specifications. These include congeal point (ASTM D938), needle penetration (D1321), color (ASTM D6045), and viscosity (ASTM D445). Micro-crystalline waxes can generally be put into two categories: “laminating” grades and “hardening” grades. The laminating grades typically have a melt point of 140-175 F (60 – 80 oC) and needle penetration of 25 or above. The hardening grades will range from about 175-200 F (80 – 93 oC), and have a needle penetration of 25 or below. Color in both grades can range from brown to white, depending on the degree of processing done at the refinery level. Micro-crystalline waxes are derived from the refining of the heavy distillates from lubricant oil production. This by product then must be de-oiled at a wax refinery. Depending on the end use and desired specification, the product then may have its odor removed and color removed(which typically starts as a brown or dark yellow). This is usually done by means of a filtration method or by hydro-treating the wax material.