structural:scholar_edition, information:highlighting, structural:expansion
Soap and soap makers

Hard toilet soap with a pleasant smell was invented in the Middle East during the Islamic Golden Age when soap-making became an established industry. Recipes for soap-making are described by Muhammad ibn Zakariya al-Razi (c. 865–925), who also gave a recipe for producing glycerine from olive oil. In the Middle East, soap was produced from the interaction of fatty oils and fats with alkali. In Syria, soap was produced using olive oil together with alkali and lime. Soap was exported from Syria to other parts of the Muslim world and to Europe. Two key Islamic innovations in soapmaking was the invention of bar soap, described by al-Razi, and the addition of scents using perfume technology perfected in the Islamic world.

By the 15th century, the manufacture of soap in Christendom had become virtually industrialized, with sources in Antwerp, Castile, Marseille, Naples, and Venice. In the 17th century the Spanish Catholic manufacturers purchased the monopoly on Castile soap from the cash-strapped Carolinian government. Industrially-manufactured bar soaps became available in the late 18th century, as advertising campaigns in Europe and America promoted popular awareness of the relationship between cleanliness and health.

A major contribution of the Christian missionaries in Africa, China, Guatemala, India, Indonesia, Korea, and other places was better health care through hygiene and introducing and distributing soap, and "cleanliness and hygiene became an important marker of being identified as a Christian".