what is the difference bt the various types of soap (e.g. castille, triple milled, glycerin, etc)? i'm getting into trying different types and i need to get a grasp on the basics. thanks
French Milled Soap - (or triple milled soap) Is a commercial process where soap (typically made from synthetic detergents) is made, dried into crystals then rolled three or more times through steel rollers. This repeated milling crushes the crystals turning them into a fine paste. This paste is then pressed and formed into bars. Removing glycerin from the soap is necessary to keep the soap from being too sticky and adhering to the rollers. French/Triple milled soap means that all soap bars will be identical with no variations in color and texture. True milled soap is impossible to do if you are not a commercial manufacturer with the steel rollers.
Castile soap is a name used in English-speaking countries for soap made exclusively from vegetable oil (as opposed to animal fat), although many soapmaking authorities hold that to be "Castile" soap it must be made exclusively or predominantly from olive oil. Examples of other oils that dissenting authorities hold can be used in castile soaps include coconut, almond, hemp, and jojoba. Castile soap is also sometimes called Seafarer's soap because of its broad range of uses.
Glycerin Soaps are soaps that contain glycerin, a component of fat or oil. The soap is most notably different in that it is translucent. The process for making glycerine soaps were well known as of 1857 in the Western world.
Production
Glycerin soap are made through melting and continuously heating soap until the mixture has reached a clear jelly-like consistency. The cooking process requires that the soap be partially dissolved with high proof alcohol. With home and hand-made soaps that still contains glycerin left over from saponification, the grating, melting and cooking of the soap can proceed without the addition of anything into the mixture, however sugar or additional glycerin is sometimes added. Glycerin soap can also be produced without remelting soap through directly cooking raw home-made soap.
In industrial soap-making, the glycerin is then usually removed. As such, to produce glycerin soap a good quantity of glycerin must be added back into the mixture prior to melting.
