Castile soap

Castile soap is a name used in English-speaking countries for olive oil based soap made in a style similar to that originating in the Castile region of Spain. Traditionally made with olive oil, in many parts of the world it still is. It can be either bar soap made with sodium hydroxide or liquid soap made with potassium hydroxide.

The origins of Castile soap go back to the Levant, where Aleppo soap-makers have made hard soaps based on olive and laurel oil for millennia.

It is commonly believed that the Crusaders brought Aleppo soap back to Europe in the 11th century, based on the claim that the earliest soap made in Europe was just after the Crusades, but in fact in the first century AD the Romans knew about soap and Zosimos of Panopolis described in c. 300 AD soap and soapmaking. Following the Crusades, production of this soap extended to the whole Mediterranean area.

In the 17th century the soap caused controversy in England, since it supplanted the unnamed local soap after the Spanish Catholic manufacturers purchased the monopoly on soap from the cash-strapped Carolinian government. Its ties to Catholicism caused a public-relations campaign to be established, featuring washerwomen showing how much more effective local soaps were than Castile soap. The sale of a monopoly in Protestant England to a Catholic company caused great uproar, ending with the Castile soap company eventually being stripped of the monopoly.

Early soap-makers in Europe did not have easy access to laurel oil and therefore dropped it from their formulations, thereby creating an olive-oil soap now known as Castile soap.

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Wikipedia