How is Soap Made?...One Word - Saponification

Updated: Apr 13

cartoon depiction of saponification

Have you ever wondered what soap actually consists of? How is one of our most basic commodities actually created? We have been using soap since infancy, yet most of us have never thought about this question before.

"So, how is soap made and where do we get this important salt from?"

Soap is a salt from a complex chemical reaction. (Pretty interesting...who would have thought that soap is a SALT!) Soap is made using a chemical process called saponification. In simple terms, saponification is the name for a chemical reaction between an acid and a base to form a salt. When soap is made oil or or fat (acid) is mixed with lye (base) to form soap (salt). When this happens glycerine is released - the moisturizing component of the soap. (BTW .. In most conventional soaps, glycerine is removed and sold separately causing the soap to become drying rather than moisturizing).

Soap making has been around since time immemorial. The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in ancient Babylon. A formula for soap consisting of water, alkali, and cassia oil was written on a Babylonian clay tablet around 2200 BC. In more recent history, it became part of the daily routine of housewives to make some soap which was used for every aspect of household cleaning.

black and white pic of woman cooking soap on a fire

Soap Making in Days Gone By

Soap making was part of the daily household routine at the beginning of the 20th century. Grandma would mix beef or pork fat and ashes from her cooking fires to make kettle soap. Though grandma could cook, her weighing and measuring techniques were probably by taste and her knowledge of soap chemistry was probably developed by trial and error. Soap got a bad name because it was often made with an excessive amount of caustic lye.

Pauline from nourish natural soap cutting soap

Over time the measuring techniques were refined and modernized allowing less chance of a lye heavy soap. Two distinct soap making methods emerged; cold process and hot process. In both methods, oil and fat is mixed with lye and water to create the soap. If you make soap using the cold process method, the blend of lye and fats is put directly into a mould and left to cure. It is well insulated with blankets to keep the mixture warm and the batter will naturally progress through the chemical reaction which turns the lye and fat mixture into soap. The entire process to turn the batter into soap will take up to 24 hours and then will need an additional 4-6 curing time to make sure that the lye is completely neutralized. Using cold process, there is a higher chance of a lye heavy soap if the raw soap is not left to cure for long enough.

Pauline from Nourish Natural Soap spooning soap into a mould

In the second method, hot process, heat is added to speed up the curing and neutralizing process of the soap batter. This forces the chemical reaction to happen within the space of 30 min and at the end of the soap 'cook' the finished product is neutral and no lye remains. It is recommended to still allow the soap to sit for a week or two to help dry and harden the bar but essentially the soap can be safely used immediately. This allows for less chance to create a lye heavy soap as the soap batter can be 'zap tested' for any remaining lye before putting it into the mould. It also means essential oils and other additives can be added when the soap is neutralized and cooled, allowing them to better retain their healing properties.

So you see, saponification - the backbone of soap manufacturing - can be reached in two different ways. And ultimately, they are the domain of handmade soap creators because conventional soap is made using a vastly different process. The soaps you buy in the supermarket are not considered real 'soap' because no lye is used. They are detergent bars made with petroleum (crude oil) ingredients. But more on that some other time.

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