The ancient Romans used ammonia (derived from urine) and fuller's earth to launder their woolen togas. Fullonicae were very prominent industrial facilities, with at least one in every town of any notability, and frequently the largest employer in a district. These laundries obtained urine from farm animals, or from special pots situated at public latrines. The industry was so profitable that fuller's guilds were an important political constituency, and the government taxed the collection of urine.

Modern dry cleaning uses non-water-based solvents to remove soil and stains from clothes. The potential for using petroleum-based solvents in this manner was discovered in the mid-19th century by French dye-works owner Jean Baptiste Jolly, who noticed that his tablecloth became cleaner after his maid spilled kerosene on it. He subsequently developed a service cleaning people's clothes in this manner, which became known as "nettoyage a sec," or "dry cleaning".

Early dry cleaners used petroleum-based solvents, such as gasoline (petrol) and kerosene. Flammability concerns led William Joseph Stoddard, a dry cleaner from Atlanta, to develop Stoddard solvent as a slightly less flammable alternative to gasoline-based solvents. The use of highly flammable petroleum solvents caused many fires and explosions, resulting in government regulation of dry cleaners.

After World War I, dry cleaners began using chlorinated solvents. These solvents were much less flammable than petroleum solvents and had improved cleaning power. By the mid-1930s, the dry cleaning industry had adopted tetrachloroethylene (perchloroethylene), colloquially called "perc," as the ideal solvent. It has excellent cleaning power and is stable, nonflammable, and gentle to most garments. However, perc was also the first chemical to be classified as a carcinogen by the Consumer Product Safety Commission (a classification later withdrawn). In 1993, the California Air Resources Board adopted regulations to reduce perc emissions from dry cleaning operations. The dry cleaning industry is in the process of replacing perc with other chemicals and/or methods.

Traditionally, the actual cleaning process was carried out at centralized "factories"; high street cleaners shops received garments from customers, sent them to the factory, and then had them returned to the shop, where the customer could collect them. This was due mainly to the risk of fire or dangerous fumes created by the cleaning process. At this time, dry-cleaning was carried out in two different machines — one for the cleaning process itself and the second to dry the garments.

This changed when the British dry-cleaning equipment company Spencer introduced the first in-shop machines (which, like modern dry cleaning machines, both clean and dry in one machine). Though the Spencer machines were large, they were suitably sized and vented to be fitted into shops. In general, three models, the Spencer Minor, Spencer Junior and Spencer Major, were used (larger models, the Spencer Senior and Spencer Mammoth, were intended for factory use). The cleaning and drying process was controlled by a punch-card, which fed through the "Spencermatic" reader on the machine. Also, Spencer introduced much smaller 6 kg capacity machines, including the Spencer Solitaire and one simply called the Spencer Dry Cleaning Machine, for use in coin-operated launderettes. These machines resembled coin-operated tumble dryers; to be as small as they were, they simply filtered used perc, rather than distilling it like the commercial Spencer machines. Solvent had to be changed far more frequently as, without distillation, it quickly became discoloured and could cause yellowing of pale items being cleaned. A coin-operated version of the Spencer Minor, which automatically carried out all the distillation and solvent-cleaning operations of the standard version, was available but rarely seen, likely due to its greater cost and size compared to the coin-operated machines.

During the 1970s and 1980s, Spencer machines were extremely popular, with virtually every branch of Bollom possessing either a Spencer Minor or a Spencer Junior. Spencer continued to produce machines (introducing new modular and computer-controlled models, such as the Spencer Sprint series) until the late 1980s, when the company closed. Spencer machines may still occasionally be seen.

Machines of this era were called vented; their fumes and drying exhausts were expelled to the atmosphere, in the same way as with modern tumble dryer exhausts. This not only contributed to environmental contamination, but also much potentially reusable perc was lost to the atmosphere. Much stricter controls on solvent emissions have ensured that all dry cleaning machines in the western world are now fully enclosed, and no solvent fumes are vented to the atmosphere. In enclosed machines, solvent recovered during the drying process is returned condensed and distilled, so it can be reused to clean further loads, or safely disposed of. The majority of modern enclosed machines also incorporate a computer-controlled drying sensor, which will automatically sense when all possible traces of perc have been removed from the load during the drying process. This system ensures that only the smallest amount of perc fumes will be released when opening the door at the end of the cycle.

how Romans found out that products derived from urine are able to clean clothes is beyond anyone's knowledge

I can explain that in a very detailed short- paragraph comic

Borag the Drunkard: " Hurrrr, d00d look at what i'm gunna d0"
Turket the Civilian: " MY WORD - good sir, please refrain from urinating in public. Wait, is that my toga? It's ruined!"
Borag: "shhhhhhhhh it won't hurt"

Three days later
Turket: "wow that drunkard did me a service, it's ironically cleaner"

And thus History was written.