It is a dark green, gelatinous, thixotropic substance used to clean grease, oil, printer's ink, or general persistent, hydrophobic dirt from the skin. Swarfega is used by working a small amount into dry skin, then wiping or rinsing off. As with other such cleaners, it is drastically more effective than soap or other common cleansing products at removing such dirt; Swarfega became virtually ubiquitous in environments where this kind of dirt is common, such as garages and machine shops.
Swarfega was invented in 1947 by Audley Bowdler Williamson (28 February 1916 - 21 November 2004), an industrial chemist from Heanor, Derbyshire. He had already founded in 1941 a detergent-sales company, Deb Ltd. (from "debutante", to signify the newness of the company and its products) based in Belper, and Swarfega became its main product. Before Swarfega, mechanics used a variety of brutal home-brewed cleaners such as paraffin (kerosene), sand and petrol. These removed the skin's natural oils, leading to dry, cracked skin and the risk of occupational dermatitis.
The effectiveness of Swarfega is due to the powerfully hydrophobic ingredients, notably medium-chain (C9-C16) alkanes and cycloalkanes; in combination with an emulsifier (Trideceth-5 in current formulations). These are more efficient at solubilising oil and grease than a detergent alone.
In the UK, the word "swarfega" may be used as a generic term for all similar cleaners, particularly if they have the same green jelly-like appearance as genuine Swarfega. According to the company website, the name comes from "swarf", being the old engineering term for oil and grease, and "-ega", as in "eager to remove". This may be a bit confusing, as "swarf" now commonly refers to the metal shavings and chips resulting from metalworking operations.
Deb expanded its product range and has long offered a range of products either related to detergent ingredients, or sold to the same mechanical trades. Many of these such as Jizer, a water-rinsable degreaser used for washing mechanical parts rather than mechanics, first defined the original market for a new product that has now become commonplace.
In recent years, Swarfega has lost the ubiquity it once had. There are now many competing products, a typical example being Deb's own "Suprega" and "Tufanega". This has an orange colour, emphasising its "natural" origins and citrus oil ingredients. As with its own precursors, Swarfega now raises concern over removing skin oils and so a gentler solution is sought. Some may also contain mechanical scrubbing additives, such as polymer grains.