Slippery History: How Soap Works

The basicsof how soap works

Soap is formed when an acid, derived from the fats and oils of plants and animals, is combined with an alkali. Today most soapmakers use commercially available alkali such as sodium hydroxide (caustic soda) or potassium hydroxide (caustic potash). When the fats and the alkali are combined, a chemical reaction called saponification occurs. And there you have it: soap.

And how does it work? Water has a property called surface tension. This tension is created as water molecules at the surface are pulled toward molecules at the bottom. Soap molecules have a head that is attracted to water and a tail that is attracted to dirt. The tail embeds itself in the dirt, and the head pulls itself toward the water, breaking the surface tension. When you rinse off, you wash away the soap molecules along with the dirt their tails are clinging to.

Clean ingredients

Even though they aren’t required to list ingredients, natural soapmakers such as Joshua Onysko of Pangea Organics generally do because they’re proud of them. Pangea soaps, for example, are made from a base of olive oil, coconut oil, soybean oil, and hempseed oil; naturally formed glycerin, herbs, flowers and spices; and essential oils.

What you put on your skin could be absorbed into your body, so it’s important to read ingredients. Seeing the word “organic” in a soap manufacturer’s name doesn’t guarantee all the ingredients are organic. Many people in the personal care industry believe that unless an ingredient is certified organic in California or another state with strict certification standards, it doesn’t mean much. “Coconut oil can be certified organic in Sri Lanka, but they still use DDT there, so I’d be concerned,” Joshua says.