Is Soap Made With Animal Fat? Unpacking the History and Process
The question “Is Soap Made With Animal Fat?” is a common one, delving into the traditional methods of soap creation that have been used for centuries. Historically, soap was indeed commonly made from animal fat, or sometimes vegetable oil, combined with a strong alkaline substance derived from plant ashes known as lye. This basic process involves a chemical reaction called saponification, where the fat or oil is transformed into soap.
At its core, soap consists of the water-dispersible portion of a fatty acid. To make soap, you essentially heat fat and mix it with lye. As water evaporates, the mixture gradually undergoes saponification, a term derived from Latin simply meaning “turning into soap.” This process typically took several days, historically ranging from 4 to 11 days. For better quality soap, an additional open-air drying time, often lasting four to six weeks, was crucial.
The active chemical compound extracted from ashes is lye. Depending on the source of the ash or the chemical used, lye can be potassium hydroxide (KOH), known as “caustic potash” (used in alkaline batteries), or sodium hydroxide (NaOH), known as “caustic soda” (used in soap making and petroleum refining). Historically, soap used for cleaning was often made with sodium hydroxide.
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Following the initial saponification, the next step involved removing impurities and glycerin (C3H8O3). This purification was necessary before the soap was suitable for use. Modern industrial processes achieve this through various methods involving agitation with alkali and other ingredients.
Traditional bar of soap, illustrating the final product of the soapmaking process.
While time-consuming, the traditional soapmaking process wasn’t overly complicated. A personal anecdote from World War II highlights its practicality: during wartime shortages of soap and meat, fat scraps were saved and used by neighbors to make soap. This simple method was effective enough for basic hygiene.
Soap only became a commercially viable product on a large scale after the invention of the Leblanc process in 1790. This innovation allowed for more efficient production of soda ash from brine, enabling the mass manufacturing of soap in commercial quantities, moving beyond small-scale home production.
How Soap Works
Understanding how soap cleans involves understanding its chemical interaction with water and grime. Soap dissolves in water, reducing the water’s surface tension and increasing its ability to penetrate and loosen dirt. The cleaning process typically involves these steps:
- The surface requiring cleaning is wet with water.
- Soap is applied and absorbed onto the surface and the grime.
- The soap molecules help lift the grime, suspending it within the water.
- Rinse water carries away the mixture of soap and suspended grime from the surface.
The History of Soap
The use of substances that function like soap dates back to ancient times, although not always explicitly recognized as a general cleanser. Sumerian texts suggest procedures for treating wounds involved heating fat or resin with lye or plant ash, which would have produced a form of soap. Ancient Egyptians, while contemporary with the Sumerians, used naturally occurring sodas or absorbent clay for general cleaning, though they may have adopted the idea of using boiled fat and alkali for wound treatment.
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Soap was recognized for its cleaning properties by the 2nd century AD. The Roman physician Galen (c. 130–200 AD) noted its use in personal hygiene, although widespread adoption for this purpose was slow. By the European Middle Ages, soap was commonly made at home, primarily for laundry. However, the strong lye used in homemade soap likely made it irritating for skin use, a characteristic still true of some lye-based laundry soaps today.
Commercial bar soap, similar to what we use today as “toilette soap,” appeared in the 19th century. Before this, however, similar products like “Soap of Damascus” were produced in Syria for a considerable period, demonstrating earlier commercial-scale soap production.
In the United States, liquid hand soap, developed in 1865 but gaining popularity in the 1980s, now dominates the market, accounting for about two-thirds of sales in the soap, bath, and shower product category. Bar soap constitutes the remaining third. Critics point out that liquid soap’s plastic dispensers and the tendency for users to use more product than needed make it less environmentally friendly than bar soap. Furthermore, some antibacterial chemicals previously marketed for their hygiene benefits, such as triclosan and triclocarban, have been banned by the FDA due to insufficient evidence of long-term safety and efficacy.
(The mere fact that human populations thrived and reproduced before the widespread availability of modern soap to mitigate body odor has been humorously termed a “triumph of biology over aesthetics.”)
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In conclusion, while soap traditionally was made with animal fat, the process is a chemical one (saponification) that transforms the fat. Modern soap can be made from various fats and oils, and its history spans millennia, evolving from basic home production to complex industrial processes and diverse product forms like bar and liquid soap.
Sources include:
MAJNO, Guido 1975 The healing hand: man and wound in the ancient world. Cambridge MA: Harvard U. Press.
“Mr. Green” 2017 Is liquid soap worse than bar soap? Sierra, July-August 2017: 12.
Photos by DKJ
