Document Author: Merv Fingas

This paper is a review and update of oil spill solidifiers and summarizes data on solidifier effectiveness, composition, and application.

Herding agents are surfactant mixtures or singular surfactants, used to drive thin slicks of oil to a desired location or to push slicks together so that they can be collected or burned. Herding agents contain a surfactant which has a spreading pressure greater than that of oil. Historically these agents were not used to any extent. Recently they have been tested as agents which may assist the burning of oil in ice situations. The idea is that the herding agents may push the oil together to yield burnable thicknesses in those cases where it is too thin to burn. Herding agents have limitations such as they are not useful in any but calm conditions and the limitation is that only about a 3 mm slick can be herded together. Further, the herding effect diminishes with time as the surfactants dissolve slowly or adhere to solid objects in their path. Action is probably limited to about one hour. Herding agents would be used by spraying them around the slick to compress the slick inward. At this time, herding agents are not approved for use in the USA nor are they common commercial products.

Surface washing agents or beach cleaners or shoreline cleaning agents, are formulations containing surfactants and are designed to remove oil from surfaces such as shorelines. The desired mechanism is that of detergency rather than dispersion. These agents generally have properties different from dispersants and are of typically lower aquatic toxicity, do not disperse oil except at higher mixing energies and are applied quite differently than dispersants. Surface washing agents are typically applied on oil stranded on beaches during low-tide phases and then the oil is removed using low-pressure water and directed toward an oil recovery area. This version of the report reviews the old work and updates the topic until 2013.