The Science Behind It—How Ammonia in Urine Acts as a Detergent
At first glance, the idea of using urine as a cleaning agent might seem bizarre, but the ancient Romans understood something fundamental about chemistry long before modern science confirmed it. The secret lay in ammonia, a powerful alkaline compound that forms when urine decomposes. Urine initially contains urea, a waste product from the human body. Over time, bacteria break down urea into ammonia and carbon dioxide, creating a pungent, highly effective cleaning solution. This natural process made stale urine far more valuable to Roman fullers—the professional laundry workers—than freshly produced urine.
Ammonia is an excellent degreaser, capable of breaking down oils, fats, and organic stains embedded in fabric. In an era where soap was not yet widely available, ammonia-rich urine provided a natural alternative for removing dirt and brightening textiles. Roman fullers collected urine from public urinals and mixed it with water to create a potent cleaning solution. Clothes were soaked in this mixture, then subjected to vigorous stomping in a process known as the saltus fullonicus, or “fuller’s jump.” This physical agitation, combined with ammonia’s chemical properties, ensured that grease, sweat, and grime were lifted from the fabric.
The effectiveness of ammonia as a detergent is still recognized today. Many modern cleaning products contain ammonia for its ability to cut through grease and neutralize acidic stains. While modern detergents use synthetic surfactants, the Romans’ use of urine was an early example of leveraging chemistry for practical purposes. Their ingenuity in harnessing natural chemical reactions speaks to the sophistication of their understanding of hygiene and textile care.
The Role of Fullers—The Professional Roman Laundry Workers
In ancient Rome, laundry was not a household chore—it was a profession. Fullers, known as fullones, were skilled workers responsible for cleaning clothes, processing fabrics, and even dyeing garments. They operated in dedicated laundries called fullonicae, which were widespread in cities like Pompeii and Ostia. These establishments functioned much like modern laundromats, except their primary cleaning agent was urine, valued for its ammonia content.
The fulling process involved several stages. First, clothes were soaked in tubs containing a mixture of water, urine, and other alkaline substances. Fullers then performed the saltus fullonicus, or “fuller’s jump,” a technique that involved stomping on the garments barefoot to loosen dirt, grease, and stains. After this, clothes were rinsed in a sequence of connected basins with fresh running water. The final stage involved brushing garments with thistles or hedgehog skin to soften the fabric, followed by a sulfur treatment to whiten them.
Despite their essential role in Roman society, fullers were often looked down upon due to their association with waste. However, they were well-organized, forming guilds known as collegia, which provided them with economic stability and social recognition. Their work ensured that Rome’s elite could maintain pristine white togas—an important status symbol in Roman culture.
The Urine Tax—How the Empire Profited from Bodily Waste
The Roman Empire had a knack for turning the mundane into a lucrative enterprise, and few examples illustrate this better than the Vectigal Urinae, or urine tax. Introduced by Emperor Nero and later reinforced by Vespasian in the late 1st century CE, this tax targeted those who collected urine from public latrines to sell for industrial purposes. At the time, urine was a valuable commodity, used in everything from tanning leather to laundering clothes, thanks to its high ammonia content.
The tax was particularly relevant during Vespasian’s reign (69–79 CE), a period when Rome was recovering from civil war and financial instability. To bolster state revenue, he imposed levies on urine collection and resale, ensuring that even bodily waste contributed to the empire’s coffers. His pragmatic approach was famously challenged by his son, Titus, who found the tax undignified. In response, Vespasian held up a coin and remarked, **”Pecunia non olet”**—”Money doesn’t smell.” The phrase endures today as a testament to economic practicality over sentimentality.
Beyond its financial benefits, the tax also influenced urban infrastructure. Public urinals, known as vespasianae, proliferated across Roman cities, providing a steady supply of taxable urine. The system exemplifies Rome’s ability to monetize everyday necessities, reinforcing its reputation for administrative ingenuity.
Public Urinals and the Collection of Urine for Cleaning Purposes
The ancient Romans were nothing if not resourceful, and their approach to laundry was no exception. Without modern soap, they relied on urine—yes, human urine—as a vital cleaning agent. But where did they get the vast quantities needed to wash the city’s garments? The answer lay in an organized system of public urinals and street-side collection jars. Fullers, the professional laundry workers of Rome, strategically placed large ceramic pots on busy street corners, particularly near taverns (tabernae) where passersby were likely to make a “donation” after a night of drinking. The collected urine was then transported to fullonicae (laundries), where its ammonia content helped break down dirt and grease from clothing.
This system was so essential to Roman industry that Emperor Vespasian even imposed a urine tax (vectigal urinae) in the 1st century CE, recognizing its economic value. Despite the undeniable usefulness of urine in the cleaning process, the profession of fullers carried a social stigma due to their daily dealings with bodily waste. Still, their work ensured that Rome’s elite could parade through the Forum in gleaming white togas—thanks, in part, to the city’s public urinals.
How Roman Laundry Methods Compared to Other Ancient Societies
The Romans weren’t the only ancient civilization concerned with clean clothes, but their methods were certainly among the most unique. While many societies relied on water and natural detergents, the Romans took a more, let’s say, unconventional approach—urine. In contrast, the Babylonians, as early as 2800 BCE, used soap-like substances made from animal fats and wood ash, a method that more closely resembles modern soap production. The Greeks, on the other hand, favored washing clothes in water mixed with alkaline substances but didn’t develop large-scale public laundry facilities like the Romans did.
What set Rome apart was its fullonicae—public laundries where professional fullones washed garments, primarily using a mixture of water, fuller’s earth, and urine. Unlike individual household washing seen in many other cultures, Roman laundry was a communal effort, facilitated by strategically placed jars for urine collection in public streets. This large-scale system allowed for efficient cleaning, particularly of woolen garments, which were a staple of Roman attire.
Compared to later European practices, such as the washboards and lye soap of the 19th century, Roman methods were surprisingly sophisticated. Their use of ammonia-rich urine as a natural detergent, combined with techniques like the saltus fullonicus (the fuller’s jump), demonstrated an advanced understanding of fabric treatment. While the thought of laundering garments in urine may seem unappealing today, the Romans’ resourcefulness in hygiene and textile care was unmatched in the ancient world.
The Social Status of Those Who Worked in the Fuller’s Trade
The fullers, or fullones, occupied a peculiar position in ancient Roman society—both essential and marginalized. Their work in fullonicae, the Roman laundries, was crucial for maintaining the crisp whiteness of the togas worn by Rome’s elite, yet the nature of their labor placed them among the lower social classes. Handling urine and other strong-smelling cleaning agents meant that fullers were often looked down upon, despite providing an indispensable service. Their profession was physically demanding, requiring them to stomp on fabric in vats of urine—a process known as the saltus fullonicus, or “fuller’s jump”—to remove dirt and grease from garments.
Despite their low status, fullers wielded some economic and organizational influence. They formed trade guilds, such as the Corpus Fontanorum in Ostia, which provided them with a degree of collective bargaining power and community support. Many fullers were freedmen, former slaves who had earned their independence and sought economic stability through skilled labor. They also had religious ties, often worshipping Minerva, the patron goddess of artisans and craftsmen. While their work was considered unpleasant, their role in maintaining Rome’s textile economy granted them a level of financial stability that many other laborers lacked.
Why This Practice Faded Away with the Rise of Modern Soap
For centuries, urine played a crucial role in the Roman laundry industry, valued for its ammonia content that effectively broke down stains and grease. However, as civilizations advanced, this practice gradually disappeared. The primary reason? Soap. Unlike urine, soap—made from animal fats and plant ashes—offered a more efficient and socially acceptable alternative for cleaning fabrics. By the early medieval period, soap production had become widespread across Europe, particularly in regions like Spain and Italy, where olive oil-based soaps emerged as a luxury good. This shift meant that fullers, the professional Roman laundry workers, no longer needed to rely on urine as a primary cleaning agent.
Technological advancements also played a significant role. The Industrial Revolution brought mechanized washing techniques and chemically synthesized detergents, making traditional urine-based laundering obsolete. By the late 19th and early 20th centuries, washing machines and mass-produced soap had become household staples, eliminating the need for manual, ammonia-based cleaning methods. Additionally, changing hygiene standards contributed to the decline of urine use in laundry. As societies became more aware of bacterial contamination, public health discourse increasingly discouraged the use of bodily waste in domestic processes. By the time modern detergents emerged in the mid-20th century, the idea of washing clothes with urine had long been relegated to history.
