Soap is made by mixing an alkali (lye) with oil or fat in a process known as saponification. Commonly used oils include vegetable oils and non-vegetable oils.
- palm oil
- rice bran oil
- ground nut oil
- castor oil
- coconut oil
- palm kernel oil
- tallow (beef fat)
- lard (pig fat)
Common bar soaps contain the most aggressive surfactants, meaning they do the best job of picking up dirt and grime from the skin to be washed away. However, these surfactants do not rinse completely away and they have a high pH, making them the most irritating to the skin. Ingredients found in ordinary soap bars include:
- sodium tallowate
- sodium cocoate
Superfatted soaps are created by a process called incomplete saponification. This is achieved by adding chemicals to the usual saponification process that prevents some of the oil or fat from being processed. Superfatting improves the moisturization of the product and makes it less irritating.
Transparent soaps are actually common bar soaps that have added glycerin, a moisturizer. The soap component of transparent soaps is still very irritating, but overall the glycerin makes transparent soaps much milder.
Syndet bars are made from synthetic surfactants. These surfactants are made from oils, fats, or petroleum products that are processed in some way other than saponification. These synthetic surfactants make syndet bars the mildest personal cleansing bars. Dove®, which was launched in 1955, was the first syndet bar produced. Common ingredients found in syndet bars include:
- sodium cocoyl isethionate (the most widely used)
- alpha olefin sulfonates
- alkyl glyceryl ether sulfonate
- sodium cocoyl monoglyceride sulfate
Combination bars are just what they sound like. They are a combination of different types of cleansers designed to maximize cleaning while minimizing irritation. These bars are commonly combinations of superfatted soap and syndet bars. Combination bars are less irritating than soaps, but less mild than syndet bars.
Abbas, Syed, Goldberg, Jessica, and Massaro, Michael. "Personal cleanser technology and clinical performance." Dermatologic Therapy. Vol. 17 2004: 35-42.
Ananthapadmanabhan, K., et al. "Cleansing without compromise: the impact of cleansers on the skin barrier and the technology of mild cleansing." Dermatologic Therapy. Vol 17 2004: 16-25.