In the modern world, soap is used for cleaning people and a few other things because nothing else works better. Despite a history of almost 5,000 years, this wasn’t always what folks believed. Over the ages, views of this household necessity changed, and the result is an interesting tale.
The Birth of Soap
The oldest known example of soap goes back to Sumeria around 4800 B.C. Traces of the material in clay pots have been found by archaeologists. Later, a clay tablet from 2200 B.C. gives a crude recipe for soap that combines oil from the cassia plant with ashes. Even today, this basic formula of mixing an alkali with fatty acids lies at the heart of soap. Bringing these two substances together creates a material that bonds with grime on one end of each molecule while bonding with water at the other to carry dirt away when washed. It appears this ancient version of soap was mainly used to clean wool and treat skin diseases by cleaning the infected areas. These uses were common along with bathing among the Egyptians when they created their own version around 1500 B.C. that substituted alkaline desert salts for wood ash.
No, the Romans didn’t rely much on soap. Instead, they preferred rubbing themselves with olive oil to loosen dirt and scrape the gunk off with a scraper called a strigil. Romans, as well as the Celtic and Germanic barbarians, knew the art of soap making. In fact, the recipe used by these barbarians, a combination of tallow and ashes, was considered superior by the Romans. This prompted them to adopt the Germanic word sapo for this substance. Sapo eventually became the word soap. In the meantime, believe it or not, the Romans used soap primarily as a type of hair gel.
The downfall of the western Roman Empire in 476 A.D. brought a decline in soap production just as with other technologies like glass and brick making. It didn’t help that the Medieval Church associated bathing with Roman paganism. Fortunately, its popularity rebounded in subsequent centuries as the nobility placed increasing importance on regular bathing. At the same time, Islam, strongly emphasizing personal hygiene, spread through the Middle East and North Africa into Spain.
An important breakthrough came in 1790 when Nicholas Leblanc of France discovered how to create an alkaline from ordinary salt which made soap more affordable. During the 19th century, global trade allowed cheap ingredients like palm oil to reduce the unpleasant odor of animal fat-based soap. Also, the Industrial Revolution greatly reduced the cost of soap manufacture. Finally, military campaigns by the British Empire forced the rediscovery of what ancient physicians knew about regularly washing with soap to control diseases. With soap a common household item by the start of the 20th century, one last breakthrough occurred during WWI when shortages in Germany forced chemists to invent ways of manufacturing soap from completely synthetic materials. The results are known as detergents.