The main solvent: perchloroethylene and its alternatives

The primary chemical in most dry cleaning is perchloroethylene (also called tetrachloroethylene or PERC), a solvent that dissolves oils and stains without using water. PERC has been the industry standard for decades because it works quickly, doesn't shrink fabrics, and leaves clothes feeling soft. However, it is a volatile organic compound—meaning it evaporates into the air—and the EPA classifies it as a likely human carcinogen.

Because of health and environmental concerns, some dry cleaners have switched to alternative solvents. Hydrocarbon solvents (petroleum-based liquids similar to mineral spirits) are now used by many facilities. These are less toxic than PERC but still flammable and require careful handling. Liquid carbon dioxide and siloxane are newer options that produce fewer emissions, though they are less common and more expensive. A few cleaners use wet cleaning—a water-based process with specialized detergents and equipment—though this works best on certain fabric types.

Key Takeaways

  • Perchloroethylene (PERC) is the most widely used dry cleaning solvent and is classified by the EPA as a likely carcinogen, though exposure levels in cleaned clothes are generally low.
  • Hydrocarbon solvents, liquid carbon dioxide, and siloxane are alternatives to PERC, each with different environmental and health profiles.
  • Finishing chemicals—including starch, sizing, and optical brighteners—are applied after cleaning to restore fabric appearance and feel.
  • Spot removers and pre-treatment chemicals target specific stains before the main cleaning cycle begins.
  • You can ask your dry cleaner which solvent they use and whether they offer PERC-free cleaning if you have health concerns.

Finishing chemicals that restore fabric appearance

After the main solvent wash, dry cleaners explore finishing chemicals to restore the look and feel of your clothes. Starch and sizing are the most common—these are stiffening agents that make fabrics crisp and help them hold their shape. Starch is often corn-based, while sizing can be synthetic polymers. Both wash out when you launder the garment at home.

Many cleaners also use optical brighteners (also called fluorescent whitening agents), which are dyes that make whites appear brighter and colors more vivid under light. These are the same chemicals found in some laundry detergents. Fabric softeners and antistatic agents reduce wrinkles and static cling. These finishing chemicals remain on the fabric until washing but are generally recognized as safe for consumer use in the amounts applied.

Spot removers and pre-treatment chemicals

Before clothes enter the main cleaning tank, dry cleaners treat visible stains with specialized spot removers. These vary depending on the stain type—oil-based stains may be treated with hydrocarbon solvents or PERC applied directly, while protein stains (blood, sweat) may be treated with enzymes or alkaline solutions. Some facilities use citrus-based solvents (d-limonene) for grease and oil, which are less toxic than petroleum solvents.

Dry cleaners also use detergents in the cleaning solution itself—these are surfactants that help the solvent penetrate fabric and suspend dirt particles. Unlike laundry detergent, dry cleaning detergent is formulated to work in non-aqueous solvents. The specific detergent chemistry depends on the solvent being used and the types of fabrics being cleaned.

Pressing and finishing chemicals

After cleaning and drying, clothes are pressed with steam or heat. Some facilities explore pressing oils or silicone-based lubricants to the pressing equipment to prevent sticking and give fabrics a smooth finish. These oils can transfer to your clothes in small amounts. Wrinkle-release sprays (often containing silicone or glycerin) may also be applied during the final pressing stage.

The plastic or paper covering placed on your cleaned clothes uses slip agents—typically silicone compounds—to prevent the covering from sticking to the fabric. These are applied in very small quantities and are not considered a health concern at typical exposure levels.

How much chemical residue stays on your clothes

The amount of solvent and finishing chemicals remaining on your clothes after dry cleaning is generally small. Most PERC evaporates during the drying cycle, and residual amounts decline further as clothes air out. Studies by the EPA and consumer testing organizations have found that PERC levels on freshly cleaned clothes are typically below 100 parts per million and drop significantly within 24 hours of airing.

Finishing chemicals like starch and sizing are water-soluble and wash out with your first home laundering. Optical brighteners and fabric softeners persist longer but are present in amounts similar to what you would get from using commercial laundry products. If you are concerned about chemical residue, airing clothes in a well-ventilated space for a day or two before wearing or storing them will reduce any remaining solvent odor and residue.

Regulations and safety standards for dry cleaning chemicals

The EPA regulates PERC use in dry cleaning facilities, requiring ventilation systems and limiting emissions. Individual states have additional rules—California, for example, has stricter PERC limits and has encouraged the transition to alternative solvents. The Occupational Safety and Health Administration (OSHA) sets workplace exposure limits for dry cleaning workers, who face higher chemical exposure than customers.

Dry cleaning facilities must follow specific handling, storage, and disposal procedures for solvents. Wastewater from cleaning operations is treated before being released. Consumer exposure through wearing dry-cleaned clothes is considered low risk by regulatory agencies, though some people prefer to avoid PERC-based cleaning for personal reasons or due to sensitivities.

Frequently Asked Questions

Is PERC in dry cleaning dangerous to wear?

Residual PERC on freshly cleaned clothes is typically very low, and most evaporates within hours. The EPA considers consumer exposure through wearing dry-cleaned clothes to be minimal. However, if you are pregnant, have chemical sensitivities, or prefer to minimize exposure, you can ask your cleaner about PERC-free options like hydrocarbon or wet cleaning.

What does that chemical smell on dry-cleaned clothes mean?

That smell is usually residual solvent—most commonly PERC or hydrocarbon. It is not harmful in the amounts present on clothing, but it indicates the solvent has not fully evaporated. Airing clothes outside or in a well-ventilated space for several hours will reduce the odor significantly.

Can I ask my dry cleaner what solvent they use?

Yes. Most dry cleaners can tell you whether they use PERC, hydrocarbon, or another solvent. Some facilities advertise PERC-free cleaning as a selling point. If you have health concerns or preferences about which solvent is used, calling ahead to ask is a reasonable request.

Do finishing chemicals like starch wash out?

Yes. Starch and sizing wash out completely in your first home laundering. Optical brighteners and fabric softeners persist through a few washes but are present in amounts comparable to commercial laundry products and are not considered harmful.

What is wet cleaning, and is it safer than solvent cleaning?

Wet cleaning uses water, specialized detergents, and computer-controlled equipment to clean delicate fabrics without solvents. It produces fewer chemical emissions and is gentler on some fabrics, but it does not work well on all garment types and costs more. It is not necessarily "safer"—it is a different process with different trade-offs.