Nerding Out: How Soap is Made

I am a nerd. Learning is one of my favorite pastimes. I love the History Channel, National Geographic, and anything or anyone that can tell me “how things are done…”

We can take everyday objects and products for granted, especially because of our consumerist culture and the ability to access anything we want at any time. We don’t just have one brand of mascara, we have 100; we don’t have one type of shampoo, we have 500. Sometimes having everything at our fingertips can cause ungratefulness, or boredom. Yet, in changing our perspective, we can see even the tiny things in life as works of art, and see the genius of invention behind them. Let’s take a look behind our privilege, and gain appreciation for the tenacity, creativity, and ability of humans to create.

I want to open our eyes to the history behind a product we use daily (hopefully):


The earliest recorded evidence of soap, a formula consisting of water, alkali and cassia oil was found written on a Babylonian clay tablet around 2200 BC. “Sapo” in Latin means, “soap.” An ancient Roman legend says that “soap” first took its name from a supposed “Mount Sapo” where ancient Romans were thought to have sacrificed animals. Rain would send a mix of animal fat and wood ash down the mountain; as it reached the clay soil banks of the Tiber River, it would mix and create a sudsy substance that was used to clean clothes.

In 300 AD we find the first documentation of real soap making, the best coming from Germany and Gaul. In the 7th century, soap was produced in Nablus (West Bank), and in Iraq. Soap was perfumed and colored—some in liquid form and some in solid. In the 8th century, soap making had become well known in Italy and Spain. Historical documents mention soap making both as “women’s work” and the product of “good workmen” alongside other necessities such as the goods of carpenters, blacksmiths and bakers.

A recently discovered manuscript from the 13th century details more recipes for soap making; e.g. take some sesame oil, a sprinkle of potash, alkali and some lime, mix them all together and boil. When cooked, they are poured into molds and left to set, leaving hard soap.[1] The French devised a method of making soap from olive oil, and in 1783, a Swedish chemist accidentally simulated the reaction that occurs in the present-day boiling process of soap making. He produced a sweet-tasting substance that is now known as glycerin. In 1823, a French chemist discovered the chemical nature of the ingredients used in soap.[2]
Finer soaps were later produced in Europe from the 16th century, using vegetable oils as opposed to animal fats.

In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms. Industrially manufactured bar soaps first became available in the late eighteenth century, as advertising campaigns in Europe and the United States promoted popular awareness of the relationship between cleanliness and health. Until the Industrial Revolution, soap making was done on a small scale and the product was rough. From 1789 on, soap was made in high-quality, transparent bars, factories began to open, and eventually soap powder was crated. In 1885, Unilever, one of the largest soap businesses was founded. Soap businesses were among the first to employ large-scale advertising campaigns.[3]

So what actually happens in the modern soap making process? Here it is in the simplest of terms:

Fatty acids and glycerin + water and lye = soap + water and glycerin

And what does this even mean? Soap is made by the reaction between a fat and a strong alkali such as lye (sodium hydroxide), potash (potassium hydroxide), or soda ash (sodium carbonate). Lye produces a hard bar of soap whereas potash is used for soft or liquid soaps.

1. Lye is dissolved in water and mixed with fat that has been melted into oil form.

2. This mixture is stirred until “trace” occurs on the surface; now the mixture is considered “soap batter.”

3. The batter begins to thicken over time, and is then poured into molds and left to cure–this can take up to several weeks to complete the process!

4. When a fatty acid meets an alkali, a process called Saponification happens, which creates the by-product, glycerin. Many soap companies leave the glycerin in their soap, as it helps make it more moisturizing. However, many mass commercial soap manufacturers will oextract the glycerin and sell it as a highly profitable by-product to be used in higher priced products like lotions and skin creams.

5. After the soap has cured for long enough, it is compacted into small pellets, which are part of the process of “soap finishing.” Soap pellets can be combined with fragrances and other materials and blended in a mixer. The material is taken from the mixer and put into a refiner that forces it through a fine wire screen.  From the refiner, the soap passes over a roller mill (French milling or hard milling). It is then put into a long log or blank and cut to whatever length desired. After passing through a metal detector, it is stamped into shape by refrigerated tools. [4]

So next time you are at a party making small talk, perhaps you can ramp up the conversation with some interesting nerdy facts about soap.


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Sarah is creative director and Editor-in-Chief of Darling Magazine. She lives in Los Angeles with her husband, and is a lover of well told stories, Chai tea, cats, nature, and Paris.