Olive oil soap
Olive oil soap describes the ingredient used to make “Castile”
soap. Named for the Castila region in Spain, Castile soap is traditionally
made from at least 80% olive oil; purists would say it has to be 100%
olive oil.
Many modern soapmakers, however, refer to any soap made from vegetable
oils as “Castile”. But the historical Castile is strictly
olive oil soap. Olive oil is prized in soapmaking for its mild, moisturizing
effects. Since the mid-16th Century, Castile soap was imported out of
Spain to royalty all over the world.
Olive oil soap doesn’t lather very well, though, which is a big
reason why it has fallen out of favor with modern society. People complain
that it feels slimy and doesn’t feel like it rinses off well.
However, it is a myth that you have to have a lather for a thorough
cleansing.