thumb|Wool fat tin (adeps lanae), at the Centre touristique de la Laine et de la Mode in Verviers, Belgium
Lanolin (from Latin 'wool', and 'oil'), also called wool fat, wool yolk, wool wax, sheep grease, sheep yolk, or wool grease, is a wax secreted by the sebaceous glands of wool-bearing animals. Lanolin used by humans comes from domestic sheep breeds that are raised specifically for their wool. Historically, many pharmacopoeias have referred to lanolin as wool fat (adeps lanae); however, as lanolin lacks glycerides (glycerol esters), it is not a true fat. Lanolin primarily consists of sterol esters instead. Lanolin's waterproofing property aids sheep in shedding water from their coats. Certain breeds of sheep produce large amounts of lanolin.
Lanolin in nature protects wool and skin from climate and the environment; it is also involved in skin (integumental) hygiene. Lanolin derivatives obtained from these processes are used widely in both cosmetics and skin treatment products.
Hydrolysis of lanolin yields lanolin alcohols and lanolin acids. Lanolin alcohols are a rich source of cholesterol, an important skin lipid, and are powerful water-in-oil emulsifiers; they have been used extensively in skincare products for over 100 years.
Applications
thumb|Lanolin ointment
Lanolin and its many derivatives are used extensively both for personal care (e.g. cosmetics, facial cosmetics, lip products) and healthcare (topical liniments). Lanolin is also used in lubricants, rust-preventive coatings, shoe polish, and other commercial products.
Lanolin is a relatively common allergen, causing what is often misunderstood as a wool allergy. However, allergy to a lanolin-containing product is difficult to pinpoint, and often different forms of lanolin may not cause an allergic reaction in the same person. Patch testing can be done if a lanolin allergy is suspected. but health authorities recommend alternative methods first, including nipple cleaning, improving baby positioning, and ultimately expressing milk by hand. Lanolin is reported to have soothing properties, but there is a lack of research.
Lanolin is used commercially in many industrial products ranging from rust-proof coatings to lubricants. Some sailors use lanolin to create slippery surfaces on their propellers and stern gear to which barnacles cannot adhere. Commercial products (e.g. Lanocote) containing up to 85% lanolin are used to prevent corrosion in marine fasteners, especially when two different metals are in contact with each other in the presence of saltwater. The water-repellent properties make it valuable in many applications as a lubricant grease where corrosion would otherwise be a problem.
7-Dehydrocholesterol from lanolin is used as a raw material for producing vitamin D<sub>3</sub> by irradiation with ultraviolet light.
Baseball players often use it to soften and break in their baseball gloves—shaving cream with lanolin is popularly used for this.
Anhydrous liquid lanolin, combined with parabens, has been used in trials as artificial tears to treat dry eye. Anhydrous lanolin is also used as a lubricant for brass musical instrument tuning slides.
Lanolin can also be applied to woollen garments to make them water- and dirt-repellent, such as for cloth diaper covers.
Lanolin is used in lip balm products such as Carmex. It can irritate the lips of some people.
Lanolin is sometimes used by people on continuous positive airway pressure therapy to reduce irritation with masks, particularly nasal pillow masks that often create sore spots in the nostrils.
Lanolin is a popular additive to moustache wax, particularly 'extra-firm' varieties.
Lanolin is used as a primary lubricating component in aerosol-based brass lubricants when reloading ammunition. It is mixed warm 1:12 with ethanol, usually about 99% pure, which acts as a carrier which evaporates quickly after application, leaving a thin film of lanolin which protects against brass seizing in resizing dies.
Lanolin is used as a lubricant for leather and fur, and in polishes and protective coatings for shoes and leather goods.
Lanolin, when mixed with ingredients such as neatsfoot oil, beeswax and glycerol, is used in various leather treatments, for example in some saddle soaps and in leather care products.
Standards and legislation
In addition to general purity requirements, in the US lanolin must meet official requirements for permissible levels of pesticide residues. The Fifth Supplement of the United States Pharmacopoeia XXII published in 1992 was the first to specify limits for 34 named pesticides. A total limit of 40 ppm (i.e. 40 mg/kg) total pesticides was stipulated for lanolin of general use, with no more than 10 ppm of any individual pesticide.
Lanolin attracted attention owing to a misunderstanding concerning its sensitising potential. A study carried out at New York University Hospital in the early 1950s had shown that about 1% of patients with dermatological disorders were allergic to the lanolin used at the time. By one estimate, not differentiating between the general healthy population and patients with dermatological disorders exaggerated the sensitising potential of lanolin by 5,000–6,000 times.
The European Cosmetics Directive, introduced in July 1976, contained a stipulation that cosmetics which contained lanolin should be labelled to that effect. This ruling was challenged immediately, and in the early 1980s, it was overturned and removed from the directive. Despite only being in force for a short period of time, this ruling did harm both to the lanolin industry and to the reputation of lanolin in general.
Cryogenic scanning electron microscopy has shown that lanolin, like human stratum corneum lipids, consists of a mass of liquid crystalline material. Cross-polarised light microscopy has shown the multilamellar vesicles formed by lanolin are identical to those formed by human stratum corneum lipids. The incorporation of bound water into the stratum corneum involves the formation of multilamellar vesicles.