Text: LANOLIN is a highly refined & purified natural wool grease and originates as a unique substance secreted by sheep from special sebaceous glands in their skin so as to form a natural protective coating on the wool fibers. This unique substance, although derived from an animal is completely different to the body fat of animals. It has the physical consistency of a soft grease and can also be identified as a wax. The crude wax is removed from the wool by various washing processes and then recovered by centrifugal separators to give a product called neutral wool grease, which after intensive refining and series of other processes, yields the finished Lanolin or Wool Wax. (Other names of Lanolin are Wool Fat and Wool Wax). Lanolin is a Mixture of Esters, Di-Esters, and Hydroxy Esters of high molecular weight Lanolin Alcohols and High Molecular Weight Lanolin Acids. Lanolin however contains none of the glycerides present in Animal Fats. The Chemistry of Lanolin is simply fascinating, demonstrating Natures ability to create a protective fatty coating which chemists have failed to duplicate in performance or composition. Chemists have in fact been attracted by the large reservoir of constituent groups available in Lanolin for derivation, extraction, and modification. Lanolin's soft desirable texture is an important factor in generating it's rapid proliferation as a vehicular ingredient popular with formulators. Lanolin is thus not a simple substance but is on the other hand a complex creation of nature endowed with a rich assortment of multifunctional groups. In Lanolin the truly remarkable classic ingredient, resides a Moisturizing Emollient, a Water in Oil Emulsifier or Co-emulsifier, a Dispersing Agent, a Plasticiser and a Super Fatting Agent............ Naturally Derived From the skin For use in the Skin............ SEE Phase Change Natural Emulsifying Agents A variety of emulsifiers are natural products derived from plant or animal tissue. Most of the emulsifiers form hydrated lyophilic colloids (called hydrocolloids) that form multimolecular layers around emulsion droplets. Hydrocolloid type emulsifiers have little or no effect on interfacial tension, but exert a protective colloid effect, reducing the potential for coalescence, by: * providing a protective sheath around the droplets * imparting a charge to the dispersed droplets (so that they repel each other) * swelling to increase the viscosity of the system (so that droplets are less likely to merge) Hydrocolloid emulsifiers may be classified as: * vegetable derivatives, e.g., acacia, tragacanth, agar, pectin, carrageenan * animal derivatives, e.g., gelatin, lanolin, cholesterol, lecithin * Semi-synthetic agents, e.g., methylcellulose, carboxymethylcellulose * Synthetic agents, e.g., Carbopols® Naturally occurring plant hydrocolloids have the advantages of being inexpensive, easy to handle, and nontoxic. Their disadvantages are that they require relatively large quantities to be effective as emulsifiers, and they are subject to microbial growth and thus their formulations require a preservative. Vegetable derivatives are generally limited to use as o/w emulsifiers. The animal derivatives general form w/o emulsions. Lecithin and cholesterol form a monomolecular layer around the emulsion droplet instead of the typically multimolecular layers. Cholesterol is a major constituent of wool alcohols and it gives lanolin the capacity to absorb water and form a w/o emulsion. Lecithin (a phospholipid derived from egg yolk) produces o/w emulsions because of its strong hydrophilic character. Animal derivatives are more likely to cause allergic reactions and are subject to microbial growth and rancidity. Their advantage is in their ability to support formation of w/o emulsions. Semi-synthetic agents are stronger emulsifiers, are nontoxic, and are less subject to microbial growth. Synthetic hydrocolloids are the strongest emulsifiers, are nontoxic, and do not support microbial growth. However, their cost may be prohibitive. These synthetic agents are generally limited to use as o/w emulsifiers.

See Also: PHASE CHANGE MATERIALS; HYDROCOLLOIDS

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