Lanolin is extracted from sheep wool grease; it is a complex mixture of esters of high molecular weight lanolin alcohols (aliphatic alcohols, sterols, and trimethyl sterols) and of lanolin acids; free lanolin alcohols, acids, and lanolin hydrocarbons are minors. Lanolin alcohols and lanolin oil are recommended as superfatting agents in soaps.

Ethoxylation of the hydroxyl groups of lanolin or of its derivatives leads to hydrophilic, water-soluble lanolin compounds, offering a broad range of useful emollients to the formulator. Some moderately to highly ethoxylated derivatives, recommended for their good emolliency and moisturization properties, are processable in liquid skin cleansers with limited impact on foam profile; as an example, the 75 mol ethoxylated lanolin does not depress foam and is recommended as skin conditioner in soaps, liquid body-cleansing products, and bubble baths. Medium ethoxylates lanolin alcohols have limited impact on foam performances of body cleansing liquids; lower ethoxylates can be formulated in bars.

Propoxylated lanolin alcohols are lipophilic emollients used in soap bars and in other cleansers based on synthetic surfactants. Alkoxylated lanolin derivatives are obtained by reaction with mixtures of propylene and ethylene oxides in various ratios; they are more soluble than ethoxylated lanolin. They serve as refattening and foam stabilizing agents. Esterification of lanolin fatty acid with isopropyl alcohol provides a range of esters of various molecular weights. Medium molecular weight esters are used as superfatting agents in soaps.

Source: Handbook of Cosmetic Science and Technology - André O. Barel, Marc Paye, Howard I. Maibach