What Is Soap?

A bar of soap may seem simple, but it begins with an extraordinary transformation.

For thousands of years, people have made soap by combining oils with an alkali in a process called saponification. During this reaction, the original ingredients are transformed into something entirely new: soap.

Soap Is Made, Not Mixed

This is one of the biggest misconceptions about soap.

Soap isn't made by simply mixing oil and lye together. During saponification, those ingredients react to create soap molecules and naturally occurring glycerin.

When the process is complete, properly made soap no longer contains free lye.

The Three Basic Ingredients

Although recipes vary, traditional soaps usually begin with just three basic ingredients:

• Oils or fats
• Water
• An alkali (commonly called lye)

Different oils create different kinds of soap. Olive oil, laurel berry oil, coconut oil, and other traditional ingredients each contribute unique qualities.

Every Soap Tradition Has Its Own Recipe

One of the fascinating things about traditional soap is that every region developed recipes based on locally available ingredients.

For example:

• Aleppo soap combines olive oil with laurel berry oil.
• Traditional Marseille soap uses vegetable oils, including olive oil.
• Nablus soap is traditionally made almost entirely from olive oil.
• Greek olive oil soap celebrates Greece's long olive-growing tradition.

Different ingredients, same basic chemistry.

Why This Matters

Understanding what soap is helps explain many of the questions people ask:

• What is lye?
• Is lye still in finished soap?
• Why are traditional soaps made with so few ingredients?
• Why do some soaps feel different from others?

We'll explore each of those topics in Soap School.

Soap School Fact

The word soap describes a specific substance created through the chemical reaction called saponification. Oils by themselves are not soap, and lye by itself is not soap. Only after the reaction is complete do they become soap.

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