Stuff You Missed In History Class

Episode: A History of Soap
Hosts: Holly Frey & Tracy V. Wilson
Date: September 8, 2025

Overview

In this episode, Holly and Tracy take on a listener request to delve into the history of soap. What seems like a straightforward topic rapidly proves to be layered and complex, intersecting with traditions of hygiene, language, chemistry, culture, colonization, and even racism. The hosts move from ancient cleansers and the chemistry of saponification, through the rise of soap making as both a craft and an industry, to its entanglement with colonialism and advertising in the modern era.

Key Discussion Points & Insights

1. Why the History of Soap is Complex

• The historical record is muddled: Sources are either ultra-specific (narrowly focusing on particular cities or times) or so broad as to obscure details.
• Research is further complicated by repeated myths or half-truths masquerading as history.

“A lot of writing about soap is either really hyper-specific, like the history of the soap industry in one particular city over a specific period, or it is so broad that it's hard to pull details out of.”
—Tracy (03:11)

2. Early Cleanliness & Natural Cleansers ([04:36–07:14])

• Hygiene practices predate soap, with societies globally using water, sand, pumice, oils, and plants high in saponins.
• Plant-based cleansers (soapwort, soapberries, ivy, yucca, etc.) have been used for cleaning and medicinal purposes.
• Languages often draw their word for "soap" from the names for these early preparations.

3. What Is Soap? ([07:14–08:10])

• Soap, scientifically, is produced by a reaction—saponification—between alkalis (like lye) and fats.
• Plant preparations (ex: boiling soapberries in water) lather but aren’t technically soap unless fats and alkalis combine.

“Soap is a substance that's formed through a chemical reaction between alkalis and fats. So if somebody added soapberries to a fat like tallow, and they mixed that with an alkali like lye, that would be considered soap. But soapberries by themselves steeped in water would not.”
—Tracy (07:30)

4. Ancient Soap Traditions ([08:10–16:11])

• Sumerians & Babylonians:

  • Earliest cuneiform references (~4,500 years ago), but likely describing cleaning processes with little true “soap.”
  • Babylonian tablets detail “fats boiled with ashes”—an intentional soap, possibly for textile processing. ([09:05–10:41])

• Egypt:

  • Ebers Papyrus (ca. 3,500 years ago) describes use of oil and alkaline salts to clean and treat skin conditions.

• Roman & Gallic Soaps:

  • The legend of Mount Sapo (“soap mountain”): Dispelled as a myth—no such place in real Roman geography. ([11:01–12:41])

  • Pliny the Elder documents soap's use for coloring hair and treating skin, noting its origins with the Gauls and Germans.

    “Soap too is very useful for this purpose. An invention of the Galls...”
    —Pliny, paraphrased by Holly (12:42)

  • Pompeii “soap factory” is another oft-repeated myth tied to an 18th-century misinterpretation.

• Galen:

  • Greek physician describes soap from animal fats and lye, strongest forms made in Germany and Gaul.

5. Linguistics of 'Soap' ([15:22])

• The Latin “sapo” (soap) likely has Germanic or possibly Turkic roots, indicating cross-cultural learning about soapmaking.

6. Soap as a Craft and Industry ([20:05–28:23])

• Medieval & Early Modern Craft

  • Soap making established in the 7th–8th centuries in Arab regions, spurring hard, olive-oil based soaps (Aleppo, Marseille, Savona, Castile, Nablus).

  • Soap guilds arise; production for both home and trade, often entwined with other trades (tallow, candles, butcheries).

  • Recipe read aloud from medieval Mape Clavicula gives insight into household production methods. ([25:10])

    “Burn some good logs and spread the ashes… What comes out on the other side is lye… add oil or tallow and add lime if desired...”
    —Mape Clavicula, paraphrased by Tracy (25:10–25:54)

• Islamic Golden Age

  • Muslim chemists like al-Razi formulate gentler, pleasantly-scented olive oil soaps for personal use.

• Shift in Usage

  • Early soaps often too caustic for skin; used more for laundry, dyeing, and industry.
  • European hygiene practices shift: Bathing declines with the rise of syphilis fears, the association of baths with disease, and Christian anxiety about “foreign” ritual bathing. ([28:23])

7. Industrialization & Modern Chemistry ([33:46–37:58])

• Soapmaking grows in scale; bottleneck is alkali. French chemists (Leblanc, Solvay) develop large-scale methods for making soda ash, crucial for industrial saponification.

• French scientist Michel Eugène Chevreul uncovers the chemistry—soap forms when fats split into fatty acid salts (soap) and glycerin.

• Industrial transport (steamships/railways) enables mass production and distribution.

• Famous Brands: ([37:58])

  • William Colgate (Colgate), William Procter & James Gamble (Procter & Gamble), William and James Lever (Lever Bros.—Unilever), B.J. Johnson (Palmolive).
  • Mergers lead to giants like Colgate-Palmolive and Unilever.

8. Soap, Advertising, Race, and Colonialism ([38:56–44:52])

• As soap production scales up, it’s tied deeply to notions of “civilization” and “whiteness.”

  • Advertisements portray cleanliness (via soap) as next to Godliness; cleanliness is coded as white, European, and civilized.

    “If cleanliness is next to godliness, soap must be considered a means of grace, and a clergyman who recommends moral things should be willing to recommend soap.”
    —Pears Soap ad quoting Rev. Henry Ward Beecher (39:38)

  • Ivory soap’s “99.44% pure” becomes marketing legend tied to whiteness.

  • Ads within and without Europe and the U.S. often depict soap as a tool to “civilize” indigenous people—sometimes literally showing Black people having their skin “washed white.”

  • The soap industry exploits natural resources and labor from colonized regions, even as it demonizes local traditions and appearances.

• Global Reach and Harmful Legacies

  • Missionaries, teachers, and social reformers push soap as a measure of “civilized” status, causing cultural erasure.
  • Sometimes the very soaps being foisted on indigenous communities are made from oils extracted from their lands.

“Teachers at mission schools told indigenous children around the world that they were dirty if they didn’t use soap... an added layer was that some of the soaps they were advocating were made with culturally important oils extracted from these same communities.”
—Holly (41:25)

9. 20th Century Innovations & the Rise of Detergents ([42:13–44:52])

• Procter & Gamble and others develop processes to hydrogenate oils, leading to harder soaps and later legal battles over patents.

• World War I spurs the development of synthetic surfactants (“detergents”).

• By the late 20th century, "soap" often refers to detergents rather than true saponified fatty acids.

• Specialty Products:

  • Laundry and dishwasher detergents (less foam), first household liquid hand soap (“Soft Soap”) in 1980, and optical brighteners and enzymes.

• The Soap Opera

  • Name comes from serial dramas (“soap operas”) sponsored by soap companies in the 1930s.

10. Soap, Health, and Global Inequity ([44:52])

• Despite the legacies of colonization, access to soap and water has a proven, measurable effect on reducing infectious disease, especially diarrheal illnesses.

• Programs now exist to distribute soap to underserved communities and recycle hotel soap for those in need.

  “Washing your hands with soap and water really does help reduce the spread of numerous diseases, so a lack of access to soap and clean water can have a serious and damaging effect on public health.”
  —Tracy (44:52)

Notable Quotes & Memorable Moments

• "The existence of some kind of norm [of hygiene] seems universal, or at least pretty close to it."
  —Holly (04:36)
• “Mount Sapo is not a real place, and this legend only seems to show up in articles about the history of soap. I could not find anything that pointed back to an original Roman document..."
  —Tracy (11:29)
• “At first, these soaps were mostly made by families or members of the community for their own use, and they were and continue to be culturally important in a lot of places.”
  —Holly (23:26)
• “[In the Medieval period] soaps were more often used for things like laundry or cleaning surfaces... They had other uses as well, for making dye or solder!”
  —Tracy (24:00)
• “Soap makers also equated soap with civilization and whiteness.”
  —Holly (40:09)
• “This connection between soap availability and disease reduction has led to programs to distribute soaps... and to do things like recycle partially used hotel soaps to distribute to poorer parts of the world.”
  —Tracy (44:52)

Main Segments & Timestamps

• Introduction & Research Challenges (02:48–04:22)
• Early Hygiene Methods & Natural Cleansers (04:36–07:14)
• Defining Soap & Early Chemistry (07:14–08:10)
• Ancient References: Sumer, Babylon, Egypt, Rome, Greece (08:10–16:11)
• Soap Making as a Trade; Regional Specializations (20:05–28:23)
• Soap and Society: Decline of Bathing, Hygiene Shifts (28:23–29:33)
• Industrial Revolution: Scaling Up Soap, Key Chemists (33:46–37:58)
• Brand Legends and Industry Giants (37:58–38:56)
• Soap, Advertising, Racism, and Colonialism (38:56–44:52)
• 20th Century: Detergents, Liquid Soaps, Special Additives (42:13–44:52)
• Soap, Global Health, and Inequality (44:52+)

Final Thoughts

Holly and Tracy’s exploration reveals soap’s history is about far more than cleanliness: it’s about chemistry, myth, trade, colonialism, advertising, and social values. The story of soap touches on some of history’s messiest intersections—industrialization, imperialism, and public health—while never losing sight of its scientific, cultural, and everyday importance.

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