Robert Spear Hudson was an English businessman who popularised dry soap powder. His company was very successful thanks to both an increasing demand for soap and his unprecedented levels of advertising. After his death, the company was taken over by his son, and was later purchased by Lever Brothers.

Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are used as thickeners, components of some lubricants, and precursors to catalysts.