The dip is available as wettable powders, pastes, solutions or suspensions which are used to prepare diluted solutions or suspensions. The term is used both for the formulation itself, and the trough in which the sheep is dipped. The sheep are completely immersed in the preparation.
The world's first sheep dip was invented and produced by Mr George Wilson of Coldstream, Scotland in 1830. That dip was based on arsenic powder and was exported by Package Steamer from nearby Berwick Upon Tweed.
There are two broad classes of sheep dip: organophosphorus compounds, which were developed for chemical warfare, and synthetic pyrethroids. Organophosphorous compounds are very toxic to humans, as they travel easily through the skin. When traveling over water, containers for these sheep dips are subject to United Nations regulations which state that they must remain legible after immersion in water.
Plunge sheep dips may be a permanent in-ground structure or a steel transportable mobile dip. Invented after the permanent plunge dip was the rotating, power spray dip. These dips are redundant in the major sheep breeding countries, as the backliners and jetting provide a better alternative.
Sheep dips have been found to contaminate surrounding soil, creating environmental problems.
The term is also used in information security. It refers to a computer that is isolated from a business core network used to screen incoming digital devices. They will often contain multiple malware scanners and egress packet detection. As it is used in the documentary The Men Who Killed Kennedy, the term also refers to the intentional broadcast of misleading details about oneself for the purposes of generating a cover prior to engaging in covert information gathering.
The name is also used to refer to some brands of originally-bootleg whisky, the best-known of which is probably Original Oldbury. When confronted by authorities, it was called "sheep dip" by sellers to escape liquor taxes (see moonshine).