Sodium Hydroxide

Sodium Hydroxide is Lye. Lye is used to make soap, but is not IN soap. It is used up during the saponification process.

What it does in soap
Sodium hydroxide, commonly called lye, is required to make real soap. It reacts with oils and fats to transform them into soap and glycerin.

Why lye isn’t “in” finished soap
Lye is used up during the soapmaking process. When properly formulated, there is no free lye left in the finished bar. The sodium hydroxide is chemically converted into soap molecules during the reaction.

Finished soap does not contain active lye.

What saponification means
Saponification is the chemical reaction between fats or oils and sodium hydroxide. During this process, the fats are broken down and reassembled into soap (fatty acid salts) and naturally occurring glycerin.

Once saponification is complete, the original lye no longer exists as lye.

Why only lye-made soap is real soap
By definition, soap is the result of saponification using an alkali such as sodium hydroxide. Products made without this process—such as synthetic detergents or “soap-free cleansers”—clean differently and are not chemically soap.

This doesn’t make non-soap cleansers bad; it simply means they are a different category of product.

Common questions

• Is lye dangerous? Lye is caustic in its raw form, which is why soapmaking is done carefully. Finished soap is safe when properly made.

• Why does soap have a high pH? True soap is naturally alkaline due to its chemistry.

• Can soap be made without lye? No. Without lye, saponification cannot occur.