Today I found out that for something that’s supposed to be clean and pure, soap has a murky past. No one knows for sure when soap was first invented, although it appears to have been around since the dawn of civilization. One of the reasons it’s so hard to pin down soap’s first appearance is that it can be made with a few, simple ingredients; in fact, just an alkali mixed with fat or oil can make soap.

We know from cuneiform tablets that 5000 years ago the Sumerians were boiling ashes together with animal and vegetable fats to make a slurry that they used for cleaning. Similar recipes for soap made from alkaline salts mixed with oils have been found on Egyptian papyri dating as far back as the New Kingdom (circa 1500 B.C.).

Although there is no proof of it, an old Roman wives’ tale holds that women who lived near Mount Sapo discovered soap when rain washed a combination of wood ashes and animal fat into the clay soil by the Tiber River where they were doing laundry. The famous Roman natural historian, Pliny, disputed this claim and credited soap’s invention to the Gallic and Germanic tribes the Romans encountered during their conquests. In any event, what is more definitively known is that Romans were using soap in their baths by 200 A.D.

After Rome fell to the barbarians in the late fourth century A.D., soap use dropped precipitously. One of the few institutions remaining in the west, the Roman Catholic Church, discouraged bathing because it was seen as too like the hedonistic and pagan ways of the old empire. Many people followed this advice, and the general lack of hygiene and sanitation is now thought to be a primary contributor to the spread of the Black Death (1348-1350), among other diseases.

Nonetheless, some people were bathing with soap even during the Middle Ages. For example, the Crusaders developed a taste for soap and brought the recipe to make Aleppo soap from olive oil back to Europe from the Middle East; as a result, soap making flourished in Spain during the 11th and 12th centuries, where Spanish Muslims made Castile soap. Likewise, soap made from wood ash was produced in some of the larger towns in England during the 13th century, and by the 1400s, French mysophobes were making Marseille soap by mixing seawater, ash and olive oil.

Prior to the 18th century, however, soap use still was not wide spread. Not only was it too expensive for everyone but the wealthy, but most soap had an unpleasant aroma as well. Luckily, with the industrial revolution came new methods of producing soap, and with the importation of exotic, fragrant ingredients from Africa and Asia, such as palm and coconut oils, soap became more appealing.

Many claim that the real turning point in making soap ubiquitous came during the mid-19th century. Early in the Crimean War (1854-1857), fought by the British in what is today the Ukraine, most of the deaths the British suffered came from disease rather than battle wounds. After Florence Nightingale brought hygiene into British field hospitals in late 1854, however, British deaths decreased. This lesson was not lost on Americans who, during their Civil War (1861-1865), instituted hygienic reforms among soldiers. Having become accustomed to regular soap use, soldiers returning from battle brought their new, clean habits home.

The rise in soap use also coincided with the development of mass marketing. One of the early giants in the commercial manufacture of soap, Proctor & Gamble (P&G), realized the importance of creating a brand, having an appealing package and then advertising the product on a mass scale. According to reports, P&G spent more than $400,000 a year on advertising in the early 1900s, an amount equivalent to $10,000,000 today. (This advertising was so ubiquitous that daytime drama serials began being called “Soap Operas”.)  That money was well spent, and by 1930 the demand for P&G soap was so great, it was being made in boilers that were three stories tall.

Today, bar soap is made in a three-step process. First, oils and fats are combined with alkali to produce a mixture of neat soap, water and glycerol in a method called saponification. Next, the mixture is dried to greatly reduce its water content. Lastly, the dried, plain soap is mixed with fragrance, color and other additives, and then extruded into bars.

Modern soap is not limited to bars, however, with liquid soap and hand sanitizer quickly overtaking the market. In fact, in 2011 Americans spent more on liquid soap than bar soap, and experts predict that hand sanitizer sales may exceed $400 million by 2015. So this begs the question, which soap should I use? The answer is harder to find than you might think.

The Centers for Disease Control (CDC) has approved hand sanitizer for health care workers as a good alternative to soap and water; however, this recommendation is not necessarily good advice for the general public. One reason the CDC encourages doctors and nurses to use sanitizer is that they need an easy and quick way to clean often, or else they might not. Most people don’t have this concern.

On the other hand (pun intended), health care workers are typically only cleaning germs from their hands, not hard-to-remove food, grease, soil and fecal matter that people also get into; according to the Food and Drug Administration (FDA), nothing cleans this gunk as well as the combination of soap, water and friction that comes with traditional hand washing.

Whatever you use, be sure to change the bar or dispenser often. According to research published in the journal, Applied and Environmental Microbiology, dispensers, and presumably soap bars, are “prone to bacterial contamination.” The study, which measured the amount of bacteria on people’s hands before and after washing with liquid soap from refillable dispensers, revealed that the elementary students and staff studied had more bacteria on their hands after washing with soap from the dispenser. Eww!

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