Lanolin is a natural moisturiser with powerful emollient and protective properties. Humans have valued its well-tolerated beneficial qualities for thousands of years. Nowadays this unique, created by nature substance is widely used in many products and various technical applications.
Generally, the term ‘lanolin’ refers to wool wax in its refined form. In the pharmaceutical industry, however, ‘lanolin’ traditionally describes a water-in-oil (w/o) emulsion with a water content of approximately 30% by weight. The waxy raw material is also known as:
Wool grease, the common term for this substance, is actually a misnomer. Chemically speaking, the greasy raw material is not a fat but a wax, because it lacks the glycerol content typical of body fat. In order to avoid confusion, we refer to the refined, waterless substance as ‘lanolin anhydrous’
Over the course of history, humans have valued sheep as a source of food, milk and clothing. They have been domesticated for 11,000 years, making sheep the oldest domestic animals, second only to the dog. Throughout this long association, humans have found a use for almost every product supplied by sheep. This includes the waxy material that coats sheep’s fleeces and has amazing moisturising properties: lanolin. Today, there are around 1.1 billion sheep on Earth. In New Zealand, they outnumber humans by an enormous margin, with 3.9 million people to 45 million sheep.
The unique nourishing and moisturising effect of wool grease on animal and human skin has been valued since antiquity. The first written mention of its use dates back to the 1st century, when Dioscorides, the Greek medic and pharmacologist, described it under the name Oesypus. In his work Materia Medica (Medical Matter), he details a technique of extracting wool grease from the hot washing liquids of sheep wool. During the Middle Ages, Oesypus was included in several pharmacopoeias, among them the Dispensarium Coloniense of 1565. Unrefined wool grease was recommended for use as a medicinal ointment for wound-healing bandages.
In the first half of the 19th century lanolin use decreased, which was probably due to improved wool scouring techniques. To produce wool of high purity new detergents, such as soap, potassium carbonate and soda, were widely used in the scouring process. These substances changed the lanolin’s usual properties; the washing water, along with its valuable wool fat, was simply poured away. Only in the second half of the century it was possible to obtain the wool grease needed at the time, thanks to the rapid development of organic chemistry.
In the 1880s, Oscar Liebreich and Otto Braun developed a method to further refine and purify wool grease by using a centrifugal process. They patented their new product under the name lanolin, based on the Latin words for wool (lana) and oil (oleum).
Lanolin became a popular and widely used ingredient in medical preparations. A large number of scientific articles were published on the substance and, in particular, about its use in medicine.
In the 20th century, lanolin became an integral part of various cosmetic and medical preparations.
The harvested wool wax is a dark, highly viscous and greasy paste. In this crude form, it can be used in several technical applications. However, due to the colour, peculiar odour and sizeable amount of impurities it retains at this stage, the wool wax must be refined further before it can be used in cosmetic products and by the pharmaceutical industry.
Some of the characteristics of wool wax that make it so valued actually complicate the refining process. For example, the powerful surfactant activity – one of the most highly regarded properties of refined lanolin – makes the purification process difficult. Impurities may be retained in microscopic droplets of oil in reluctantly formed water-in-oil (w/o) emulsions, which are very difficult to break up. To counteract this, the emulsifying power of the wax has to be held to a low and controlled level during the refinement process, without impairing the product quality.
The techniques and materials used for refining lanolin vary from processor to processor. Generally, the first step involves the break-up of soaps and removal of acid-soluble impurities by refluxing the crude wool wax in an aqueous acid solution. After separation and disposal of the aqueous phase, the free fatty acids in the wax are neutralised via an alkaline treatment, preferably using a sodium hydroxide or carbonate solution. The resulting soaps, which are formed by the reaction of fatty acids with alkali metal ions such as sodium, can be extracted using mixtures of ethanol or isopropanol with water. The alcohols function both as a co-solvent and an agent to reduce the emulsifying properties of surfactant molecules. This makes sure that undesired materials are washed out of the wax mixture effectively.
Depending on the desired purity grade, this extraction procedure can be repeated with more highly concentrated alcohol mixtures. A further reduction of contaminants can be achieved through treatment with adsorbents, such as activated carbon, followed by filtration. Residual pesticides and odours can be removed by exposure to high vacuum and simultaneous heating of the wool wax. This processing step also reduces the amount of free lanolin alcohols. By slightly varying vacuum and temperature conditions, their content can be reduced to less than 3% by weight, which is crucial if the desired result is product hypoallergenicity.
At this stage in the refinement process, most of the impurities – free fatty acids, detergents and pesticides – will be sufficiently reduced and the product will be pleasantly deodorised. The dark colour will have faded into a pale yellow tone. While the colour of the refined lanolin has nothing to do with its quality, some cosmetic applications require bright lanolin. This can be achieved by bleaching the wax with common oxidative reagents such as:
If hydrogen peroxide is used, however, undesired organic peroxide derivatives of wax esters may be formed, which require additional treatment for removal. If the lanolin is not bleached, then small concentrations of another approved antioxidant, such as butylated hydroxytoluene (BHT), are usually added at the end of the refinement process. This stops the air getting to the lanolin, preventing superficial degradation by autoxidation.
Finally, residual water is removed through a vacuum-drying process to give refined lanolin anhydrous, a pale, ointment-like substance with a scarcely recognisable odour. It is soluble in organic solvents like diethyl ether, chloroform and chloroform/methanol mixtures, but poorly soluble in ethanol. It does not dissolve in (but is mixable with) water, forming stable water-in-oil (w/o) emulsions.
Comparison: crude wool wax and refined pharmaceutical lanolin (typical compositions)
Component
Crude centrifugal wool wax
Refined pharmaceutical lanolin
Water
Crude centrifugal wool wax:
1-5% w/w
Refined pharmaceutical lanolin:
0.05% w/w
Free fatty acids
Crude centrifugal wool wax:
1-8% w/w
Refined pharmaceutical lanolin:
0.30% w/w
Free fatty alcohols
Crude centrifugal wool wax:
6-12% w/w
Refined pharmaceutical lanolin:
2.50% w/w
Wax esters
Crude centrifugal wool wax:
75-90% w/w
Refined pharmaceutical lanolin:
97.0% w/w
Water soluble salts of potassium and sodium
Crude centrifugal wool wax:
0.1-0.2 w/w
Refined pharmaceutical lanolin:
not quantified
Lipid soluble salts of calcium, magnesium, iron, aluminium
Crude centrifugal wool wax:
0.2-2.0 w/w
Refined pharmaceutical lanolin:
not quantified
Detergent residues
Crude centrifugal wool wax:
0.1-1.0 w/w
Refined pharmaceutical lanolin:
0.02% w/w
Pesticide residues
Crude centrifugal wool wax:
20-150 mg kg-1
Refined pharmaceutical lanolin:
0.8 mg kg-1
Polyaromatic hydrocarbons
Crude centrifugal wool wax:
0.1-0.5 mg kg-1
Refined pharmaceutical lanolin:
0.08 µg kg-1
Particulate insoluble matters
Crude centrifugal wool wax:
0.1-2.0
Refined pharmaceutical lanolin:
not quantified
Peroxide value
Crude centrifugal wool wax:
not quantified
Refined pharmaceutical lanolin:
12.0 meq. kg-1
Colour
Crude centrifugal wool wax:
dark brown
Refined pharmaceutical lanolin:
pale to yellow
Odour
Crude centrifugal wool wax:
peculiar smell
Refined pharmaceutical lanolin:
almost odorless
Source: E.W. Clark 1999, ‘The History and Evolution of Lanolin’
Once a sheep has been shorn, the fleece must be washed in a process called scouring. Scouring uses hot detergent solutions to remove the wool grease, which is a largely hydrophobic (water repellent) substance. The wool grease is then recovered from the scouring liquids by high-speed centrifugation. Depending on the breed of sheep, the season and the quality of the wool, crude wool grease makes up about 10-15% of the weight of the shorn fleece.
Heavy impurities such as sand and dirt are removed by gravity settlement before centrifuging. To further reduce impurities such as sweat or environmental contaminants, the first wool wax concentrate is emulsified in hot water and centrifuged a second time. The obtained substance is ‘crude wool grease’ or ‘neutral wool grease’; this is then refined to produce lanolin, the most common wool grease product.
To speed up and improve the separation of liquid and hydrophobic wax during the first centrifugation, special acids are sometimes added to the scouring solution. These cause a chemical breakdown of the soap that holds the wax in a stable emulsion. However, modern processing plants generally miss out this step because it releases free fatty acids in the process. This in turn leads to wool wax products with high acid values, which is undesirable. While only 50% of the available wool grease can be recovered by the centrifugation process, this low yield is compensated by the superior quality of the obtained raw material
As well as the standard centrifugal technique that is used by most factories, wool grease can be recovered through several alternative methods, such as solvent extraction followed by filtration and distillation.
If the grease is directly washed out of the wool by organic solvents, the yield will be generally higher and the fleece will be protected from adverse alkaline treatment.
Wool grease is naturally produced by the sebaceous glands in sheep’s skin. They continuously secrete it into the wool, coating the fibres with a protective, waxy sheath. This provides both skin and fleece with a naturally enhanced resistance against constant exposure to the elements. Over millions of years, evolution has perfected this complex mixture of thousands of lipid compounds in a process that we could describe as ‘natural bio-engineering’.
Wool grease is recovered from the liquids in which sheep’s wool is washed on a large scale. This base material is then further refined to produce lanolin and a great variety of lanolin derivatives, such as:
All of these substances share exceptional emulsifying and emollient (softening or smoothing) properties. They are widely used as moisturising ingredients in cosmetic and medical products, as well as numerous technical applications.
Essentially the by-product of sheering , lanolin is the ultimate renewable resource. It is obtained without harming the animals – a real ‘green’ material. The majority of wool produced in the world comes from New Zealand and Australia. These countries, thanks to vast and sprawling fields that are perfect for grazing, have a long tradition of raising sheep. Seasonal shearings relieve the sheep of their warm, heavy hair in a cruelty-free process that does not harm the animal. Referring to lanolin as an ‘animal derived’ product is misleading, because it doesn’t take into account the ecologically friendly advantages of this remarkable raw material.
Since it is obtained through the wool industry without harming or killing the animals, lanolin can best be described as an ‘animal harvested’ natural product. Even Greenpeace lists lanolin as a ‘green’ material in its evaluation of cosmetic ingredients.
Wool grease, the common term for this substance, is actually a misnomer. Chemically speaking, the greasy raw material is not a fat but a wax, because it lacks the glycerol content typical of body fat. Wool grease is a complex mixture of esters, di-esters and hydroxy esters formed by condensation of high molecular weight lanolin alcohols with lanolin fatty acids. The overall molecular weight ranges from 790 to 880.
After saponification, scientists have identified in lanolin:
About 40% of lanolin esters are alpha-hydroxy esters (AHEs). Approximately 1% to 8% of the fatty acids and 6% to 12% of the alcohols are present in their free, unbound form.
Considering the almost random combinations of the 69 aliphatic alcohols, 6 sterols and the 160 lanolin acids, the estimated number of lanolin mono-ester compounds that are theoretically possible exceeds 10,000 – even if calculated by leaving out di-ester compounds. The exact number of individual ester ingredients effectively present in the mixture is not known. Crude wool wax contains residues of:
Environmental contaminants, such as ubiquitous polyaromatic hydrocarbons (PAH) that are present in most natural substances, can be removed from the crude wool wax by sophisticated refining methods.
Other impurities in wool wax are a result of veterinary procedures necessary for the health of the sheep. After the animals are shorn, they are treated with agents to protect them against pests.
Only water soluble and biodegradable organophosphorous compounds are allowed for this purpose. Using persistent pesticides (such as organochlorine preparations) is illegal in all leading sheep wool production countries. In this respect, New Zealand and Australia are leaders in ecologically responsible sheep farming.
State-of-the-art engineering makes it possible for modern refineries to remove traces of contaminants, residues and other impurities almost beyond the detectable limit.
Lanolin is a well-tolerated emollient and probably one of the most marginal contact sensitisers in clinical medicine. Laboratories and clinics all over the world have studied its skin compatibility and conclude that it is not a significant allergen. In fact, considering the widespread use of lanolin and lanolin derivatives in commercial and pharmaceutical skin-care products, the incidence of skin irritation has not increased in over a century. Still, the myth of lanolin as an allergen persists, often in public discussion forums in which certain authorities mistakenly label it as a ‘leading’ sensitiser. Why is this and what is the source of this fallacy?
The answer is in the misinterpretation of a dermatological study published in 1953 by Marion Sulzberger of New York University Hospital. Sulzberger patch tested 1,048 patients suspected of contact allergy. He found that 12 individuals exhibited positive reactions to lanolin treatment, constituting a reaction rate of 1.15%. That incidence of 1.15% was incorrectly translated to the general American population, ignoring the fact that Sulzberger’s test patients, as he detailed in his study, belonged to a group “predisposed to acquire multiple specific sensitisations of the skin to eczematous allergens”. In other words, his test group was prone to skin allergies. In a control group of 120 healthy test subjects, none experienced any reaction to lanolin.
Most researchers conclude that the incidence of lanolin allergy within the general population is negligibly low, varying from approximately 10 to 1 per million. Incidence can be lowered practically to zero when the content of free lanolin alcohols is reduced to a share of 3% or less. This purified lanolin causes still fewer reactions, even among patients known to be lanolin sensitive, and fulfils the requirements for use in hypoallergenic formulations. Scientists believe that components of the alcoholic fraction are responsible for the small number of sensitisations, although the exact component has not yet been identified. Renowned skin researcher Albert M. Kligman, from the Philadelphia School of Medicine, says: “It is time to stop denigrating a wonderful natural substance, which has been used for thousands of years as a luscious emollient and an all-purpose vehicle for a great variety of skin-care products.”
It is a given that all of ImperialOel’s lanolins and derivatives are exclusively obtained from the raw wool of living sheep that have been raised and cared according to the highest standards.
As an integral link in the supply of this product, we consider it our obligation to increase awareness of lanolin as an important natural by-product of the global wool textile industry. But on top of this, the company also explores new ways to ensure that all participants in our supply chain are sharing the same awareness and understanding of animal welfare.
While having relatively small leverage to implement changes within the massive textile industry, the team at ImperialOel is constantly keeping abreast of the latest research and best practices to promote the wellbeing of the live stock along the supply chain.
As part of this aim, we focus on exploring new ways to minimise the use of mulesing. This practice is primarily found in Australia where moist and damp conditions can lead to the proliferation of Lucilia cuprina, commonly known as blowfly, which lays its eggs in sheep’s rear end skinfolds and then starts to eat away at the animal’s flesh, a condition known as flystrike. The practice of mulesing aims to limit the suffering of sheep by cutting away sections of a lamb’s rear end skin folds in order to prevent flystrike developing later on in life.
However, while mulesing exists to safeguard the sheep, there has been strong criticism from animal rights campaigners about the practice that has led to improvements aimed at enhancing the sheep’s welfare. While the mulesing has been greatly reduced throughout Australia, in areas where blowfly remains a big problem, sheep farmers have introduced methods to make the procedure less painful. Improving matters even more, concerted efforts are also being made to breed sheep that do not have any skin folds. Thanks to these efforts, where mulesing is still practiced, the wellbeing of the sheep is better ensured, while the new breeding programmes are also leading to a significant reduction in the number of lambs that need to be mulesed.
The traceability of lanolin is challenging because certification is designed around the needs of the wool industry, which means that it is often not possible to certify lanolin. However, our team has developed a number of means to ensure that high standards of traceability are followed throughout the supply chain. The wool supply chain involves a number of critical stages, during which the commodity changes hands, starting with the wool grower selling to the wool broker, who then sells it to wool processors all over the world. Following this stage the wool is either washed and combed or sold directly to the scourer and top maker to undertake these processes. The wool is then sold as top wool to a spinner who creates the yarn to sell on to the weaver or knitter to make the fabrics that are then sold to brands and retailers to make wool products.
It is because there are so many different stages before the wool is turned into a product that traceability is so difficult, but the team at ImperialOel has chosen to work with key partners within these overlapping segments of the industry in an effort to create more traceable processes. In particular we have committed to traceability as the foundation of responsibility within the context of the entire wool producing supply chain, enabling us to share with our customers how lanolin forms a part of a trustworthy and responsible industry. Ultimately, we believe in a traceable supply chain for lanolin that addresses fundamental areas such as animal welfare and the use of mulesing as well as issues like pesticide residues, without compromising the very highest standards of quality.
Chris Kommerowski Sales Director
Marco Heins Product Manager
Kruna Ramljak Product Manager
Christina Wegener Logistics and Sales Manager
Felix Wohlers Logistics Manager
