Greasy wool
Also searched as: raw wool, fleece, wool grease
Raw fleece before washing removes much of its grease and dirt.
In detail
Greasy wool is wool before raw-wool scouring removes much of its grease and accompanying contaminants. A raw fleece contains more than clean textile fiber: dirt, dust and suint, among other material, contribute to its mass. The amount varies with the fleece and its circumstances.
The science and numbers
The non-fiber fraction of a raw fleece has three main parts. Wool grease, the source of lanolin, is water-insoluble and is dominated by esters: studies describe lanolin as a source of branched-chain sterol esters and wax esters, and one analysis of scouring-effluent grease identified sterol esters as its most important components. Suint, the dried sweat, is water-soluble and rich in potassium salts; reported wool-scouring effluents contain roughly 4,200 to 13,000 mg of potassium per liter. Dirt, dust and vegetable matter make up the rest. Because the clean-fiber share varies from fleece to fleece, sale lots are sampled by coring the bales, and IWTO-28 applies the airflow method to raw-wool core samples so that mean fiber diameter can be certified before scouring. Wool grease is removed industrially by emulsifying it with detergent, which is why scouring effluent is high in chemical oxygen demand.
A practical example
If comparing a raw fleece price with a clean-fiber price, first identify the mass basis. A kilogram of greasy wool is not equivalent to a kilogram of scoured fiber. Ask whether a quoted quantity or yield refers to the material before or after cleaning.
What to distinguish
Greasy describes a processing state, not a wool breed or a softness grade. It also does not establish how the wool will perform once cleaned, spun, constructed and finished.
Origins and history
Fine wool is still traded in three forms that mark successive stages: greasy fleece, scoured wool and combed top. Certification of greasy lots matured in the late twentieth century: IWTO accepted test method IWTO-28 in 1971, allowing mean diameter of sale lots to be certified from core samples, and in 1995 accepted the Laserscan and OFDA methods for raw wool and top. The grease itself became a commodity as lanolin, and dermatologists have recognized allergy to lanolin and its derivatives for decades.
Related terms
Sources & further reading
- Woolmark: Scouring and carbonising
- Water Research: Mechanism of aerobic biological destabilisation of wool scour effluent emulsions (2005)
- Journal of Hazardous Materials: A review of the fate of potassium in the soil-plant system after land application of wastewaters (2008)
- Biochimica et Biophysica Acta: Lanolin-derived lipid mixtures mimic closely the lipid composition and organization of vernix caseosa lipids (2008)
- Woolwise: Notes, Topic 7, Fibre diameter
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.