The main solvent in modern dry cleaning is perchloroethylene, usually called perc
Perchloroethylene (perc) is the solvent used in roughly 80 percent of dry cleaning shops in the United States. It is a clear, colorless liquid that dissolves oils and grease without water, which is why it works on fabrics that would shrink or bleed if washed in a washing machine. Perc has been the industry standard since the 1950s because it cleans well, dries quickly from fabric, and was cheaper than alternatives for decades.
Perc is a chlorinated hydrocarbon—a chemical made from carbon, hydrogen, and chlorine atoms. It evaporates at room temperature, which means it leaves clothes dry and ready to wear within hours of cleaning. The solvent is recycled during the cleaning process: machines filter out dirt and lint, then distill the perc to remove dissolved oils so it can be used again. A single batch of perc can clean hundreds of loads before it becomes too contaminated to use.
Despite its effectiveness, perc has drawbacks. The U.S. Environmental Protection Agency classifies it as a probable human carcinogen, and exposure to high levels can cause dizziness, headaches, and liver damage. Dry cleaning workers who handle perc daily face the highest risk. For this reason, the EPA has been phasing out perc use, and some states—including California and New York—have set important date for shops to stop using it entirely.
Key Takeaways
- Perchloroethylene (perc) is the solvent in most dry cleaning shops because it removes oils and grease without water and dries quickly from fabric.
- Perc is recycled during cleaning—machines filter dirt and distill the solvent so it can be reused many times before disposal.
- The EPA classifies perc as a probable carcinogen, and long-term exposure poses health risks to dry cleaning workers.
- Alternative solvents like hydrocarbon and liquid carbon dioxide exist but are less common because they cost more or clean less effectively.
Why perc became the standard solvent
Before perc, dry cleaners used gasoline, benzene, and other flammable solvents that posed serious fire risks. In the 1950s, perc offered a major safety improvement: it does not burn easily, so shops could operate without constant fear of explosions. At the same time, perc cleaned better than older solvents and cost less than competing options, making it the obvious choice for shop owners.
The solvent's popularity grew through the second half of the twentieth century because the cleaning industry had no strong incentive to change. Perc worked, it was affordable, and the health and environmental risks were not widely understood or regulated. By the time the EPA began studying perc's effects in the 1980s and 1990s, the chemical was entrenched in thousands of shops across the country.
How perc actually cleans clothes
Perc works by dissolving the oils, waxes, and greasy stains that water cannot touch. When you sweat, eat, or brush against dirt, you leave behind oily residues that stick to fabric fibers. Water alone cannot break these down—it beads up and rolls off, which is why you cannot wash a silk tie or wool suit in your washing machine without ruining it. Perc molecules surround and dissolve these oily particles, lifting them away from the fabric.
The cleaning happens inside a large machine similar to a washing machine, but instead of water and detergent, it uses perc and a small amount of soap designed to work in perc rather than water. The machine agitates the clothes gently for 20 to 30 minutes, then drains the perc into a holding tank. The clothes are then spun to remove excess solvent, and warm air dries them the rest of the way. The whole process takes a few hours from drop-off to pickup.
Alternative solvents some cleaners use instead
As perc regulations tightened, some dry cleaners switched to hydrocarbon solvents—mineral oil-based liquids that are less toxic than perc but still flammable. Hydrocarbon cleans well and costs less than some alternatives, but it requires more careful handling and storage because it can ignite. A few shops use it successfully, but it has not become widespread because the fire risk makes insurance more expensive and building codes more restrictive.
Liquid carbon dioxide is another alternative that has been tested in commercial settings. It is non-toxic and non-flammable, but the equipment is expensive and the process is slower than perc cleaning. Some high-end cleaners in major cities offer CO₂ cleaning as a premium service, but the cost is typically 50 to 100 percent higher than standard perc cleaning, which limits its use to specialty garments.
Siloxane is a silicone-based solvent that some European cleaners use. It is gentler on delicate fabrics and has lower toxicity than perc, but it is not widely available in the United States and costs significantly more. A handful of shops in California and the Northeast have adopted it as perc important date approach, but it remains a niche option.
What happens to perc after cleaning
Modern dry cleaning machines include a distillation unit that recycles perc on-site. After clothes are cleaned, the dirty perc drains into a tank where heavy particles settle to the bottom. The machine then heats the perc to evaporate it, and the vapor condenses back into liquid in a separate chamber. This distilled perc is clean enough to use again, and the process repeats until the solvent becomes too contaminated—usually after 200 to 400 cleaning cycles.
When perc finally wears out, it must be disposed of as hazardous waste. Shops are required by law to store it in sealed containers and arrange for a licensed waste disposal company to pick it up. The disposal cost is one reason perc is becoming less attractive to shop owners—recycling reduces the amount of new perc they need to buy, but disposal of the final batch is expensive and regulated.
Health and environmental concerns with perc
The EPA has found that perc can contaminate groundwater if it leaks from storage tanks or is disposed of improperly. In some neighborhoods with many dry cleaning shops, perc has been detected in drinking water wells. Long-term exposure to perc in drinking water has been linked to kidney and liver damage in animal studies, though the risk to the general public from trace amounts in water is considered low.
For dry cleaning workers, the risk is much higher. Workers who breathe perc vapor for years can develop neurological symptoms, kidney problems, and an increased risk of cancer. The EPA's classification of perc as a probable carcinogen is based on studies showing that animals exposed to high levels developed cancer, and some human studies suggest a link to certain cancers in workers. This is why California banned perc in new dry cleaning shops starting in 2023 and requires all shops to stop using it by 2025.
Frequently Asked Questions
Is perc dangerous if I wear dry-cleaned clothes?
No. Perc evaporates quickly from fabric, and the small amount that might remain poses no health risk from wearing or touching the clothes. The danger is to workers who handle perc daily in enclosed spaces. If your clothes smell strongly of chemicals after pickup, you can hang them outside for an hour to let any remaining solvent evaporate.
Can I wash dry-clean-only clothes at home instead?
Some items labeled "dry clean only" can be hand-washed in cool water with gentle detergent, but the label exists because the fabric or construction may shrink, bleed, or fall apart if wet. Test a hidden area first. Delicate silks, wools, and structured garments are riskier. If you are unsure, dry cleaning is the safer choice for expensive pieces.
What should I do if I think I have been exposed to perc?
If you work in dry cleaning and have symptoms like dizziness, headaches, or nausea, talk to your doctor and mention perc exposure. If you suspect perc contamination in your drinking water, contact your local health department or water utility. They can test your water and advise you on whether a filter is needed.
Will all dry cleaners stop using perc soon?
important date vary by state. California requires shops to stop by 2025, and New York by 2024. Other states have no important date yet, so perc will remain common in many areas for years. If you prefer perc-free cleaning, ask your local shop what solvent they use—some have already switched to alternatives.
Is dry cleaning with alternatives more expensive?
Yes. Hydrocarbon costs slightly more than perc, and liquid carbon dioxide or siloxane can cost 50 to 100 percent more. Some shops offer alternative solvents only for delicate items. If cost is a concern, standard perc cleaning remains the cheapest option, though this may change as perc becomes harder to source.