How Does Dry Cleaning Work?

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The term “dry cleaner” first appeared on a list of occupations inscribed on a Mycenaean clay tablet dating from 1600-1100 BCE. Van Sigworth of the National Institute of Drycleaning posits that this likely referred to the use of grease-absorbing dirt and sand to remove stubborn stains. This was truly “dry” cleaning—a claim that can't be made about our contemporary versions.

The specifics of the story vary, but the first modern dry cleaner is often said to be a Frenchman named Jean-Baptiste Jolly or Jolly Belin (depending on whom you ask). In the early 19th century, Jolly accidentally spilled kerosene (or was it turpentine?) from a lamp onto a greasy tablecloth. When the spot dried, he noticed it was remarkably clean. After a little experimenting, the enterprising Jolly found that the petroleum-based fluid worked to wash all sorts of delicate fibers.

The first commercial dry cleaners opened in Paris in 1825 (or ’45) under the name "Jolly Belin." For the next one hundred years or so, dry cleaning companies relied on kerosene, or the equally combustible benzene and gasoline, to banish stains. The fire threat these solvents posed made it difficult for dry cleaners to obtain insurance—not to mention risky for them to operate. In the 1930s, people began experimenting with different solvents less likely to set their businesses aflame, and in 1948 the industry settled on a non-flammable halogen compound called perchloroethylene, or "perc," for short.

Wash, Rinse, Repeat

For the most part, perc is what dry cleaners still use today. After clothes are loaded into what resembles a normal washing machine, the rotating drum fills with the chemical. The machine is then agitated to scrub stains away; post-cycle, the perc drains out of the drum to be stored for another load. (Dirt is filtered out of the solvent before it drains or it is distilled later so the liquid can be used again.) At some point in the process, specific water-soluble stains are treated. Finally, clothes are pressed and returned in one of those annoyingly clingy plastic bags.

For a quick overview of this process, check out the video below:

The Problem with Perc

Perc reigned supreme as the dry cleaning chemical of choice until the mid-1990s, when a series of scientific studies delivered a hit to its reputation. (One scary Seattle-based study found that rates of esophageal and bladder cancers among dry cleaning workers increased by a factor of about two.) Today, the EPA concedes that Tetrachloroethylene (another name for perc) is “likely to be carcinogenic to humans” and “may also cause adverse effects in the kidney, liver, immune system and hematologic system, and on development and reproduction.”

Today, those searching for perc-free alternatives generally have one of three options, thanks to so-called “Organic” or “Green” cleaners. Option one is siloxane, a silicone-based chemical solvent that is biodegradable and is not believed to be a health risk. Good old-fashioned (and cheap!) hydrocarbon can be used, too, and though it’s generally thought to be safer than perc, it can leave a chemical odor on clothes. The newest (and priciest) innovation in dry cleaning uses CO2 as a solvent—although most neighborhood shops can’t yet afford the machines that convert carbon dioxide from its gas form to a liquid.

The simplest non-perc solution for businesses looking to attract conscious consumers is “wet cleaning,” in which—you guessed it—regular old water is heated to a desired temperature then used to scrub out stains.