The main chemical in most dry cleaning is perchloroethylene

Perchloroethylene, also called perc or tetrachloroethylene, is the solvent used in roughly 80 percent of dry cleaning operations in the United States. It dissolves oils and grease from fabric without using water, which is why it works on materials that would shrink or lose shape in a washing machine. Perc evaporates quickly after cleaning, leaving clothes dry and ready to wear within hours.

The chemical has been used since the 1930s because it is effective at low temperatures and does not damage most fabrics. However, the Environmental Protection Agency has classified perc as a likely human carcinogen, and the chemical can linger in the air and groundwater near dry cleaning shops. Many states have begun phasing it out or requiring stricter ventilation and disposal rules.

Key Takeaways

  • Perchloroethylene (perc) is the most common dry cleaning solvent, used to dissolve oils and grease without water.
  • Hydrocarbon solvents and liquid carbon dioxide are alternatives that some dry cleaners use instead of perc.
  • Dry cleaners also use spotting chemicals, finishing agents, and pressing compounds to treat stains and restore fabric appearance.
  • The EPA classifies perc as a likely carcinogen, and many states now regulate how it is stored, used, and disposed of.
  • Choosing a dry cleaner that uses alternative solvents or has strong ventilation can reduce your exposure to perc fumes.

Hydrocarbon solvents as an alternative to perc

Some dry cleaners use hydrocarbon solvents instead of perc. These are refined mineral oils derived from petroleum and work similarly to perc by dissolving oils and grease. Hydrocarbons are less toxic than perc and do not carry the same cancer classification, though they are still flammable and require careful handling and ventilation.

Hydrocarbon cleaning is sometimes called "petroleum solvent cleaning" or "DF-2000 cleaning," depending on the brand. The process takes slightly longer than perc cleaning and may cost more, but many dry cleaners market it as a safer option for customers and workers. The solvent still needs to be filtered and disposed of properly, and it produces some odor during the cleaning process.

Liquid carbon dioxide and other emerging solvents

A smaller number of dry cleaners use liquid carbon dioxide (CO₂) as a solvent. Carbon dioxide is a gas at room temperature but becomes liquid under pressure, and in that state it can dissolve oils and grease. This method is gentler on delicate fabrics and produces no toxic fumes, making it attractive for high-end or specialty cleaning.

Liquid CO₂ cleaning is more expensive than perc or hydrocarbon cleaning because the equipment is specialized and the process is slower. A few dry cleaners also experiment with siloxanes and other synthetic solvents, but these remain uncommon. The trade-off is always between cost, speed, fabric safety, and environmental or health risk — no single solvent is ideal for all three.

Spotting chemicals and stain treatments

Before the main solvent wash, dry cleaners use spotting chemicals to treat visible stains. These are often perchloroethylene itself, applied directly to the stain, or specialized formulas containing surfactants (soap-like compounds) that break down specific types of stains. Protein stains like blood or egg may be treated with enzymes, while oil-based stains may need a different chemical approach.

Common spotting agents include acetone for some synthetic stains, alcohol for dyes and inks, and hydrogen peroxide for bleaching. Dry cleaners choose the spotting chemical based on the fabric type and stain composition. Aggressive spotting can damage delicate materials, so the process requires skill and knowledge of how different chemicals interact with different fibers.

Finishing agents and pressing compounds

After cleaning and drying, dry cleaners explore finishing agents to restore fabric appearance and feel. These include sizing (a starch-like compound that adds body and crispness to cotton and linen) and softeners that make synthetic fabrics feel smoother. Some finishing agents are water-based, while others contain solvents or silicones.

During pressing, dry cleaners may use pressing compounds or steam pressing aids to help the iron glide smoothly and add shine. These are often silicone-based or wax-based products applied lightly to the garment or pressing equipment. The compounds evaporate or dry during the pressing process and are not meant to remain on the fabric.

How dry cleaners handle and dispose of solvents

Dry cleaning solvents are not straightforward poured down the drain. Regulations require dry cleaners to filter used solvent to remove lint, buttons, and other debris, then store it in sealed containers. The used solvent is either recycled (distilled to remove contaminants and reused) or sent to a licensed waste disposal facility.

Perc disposal is heavily regulated because of its toxicity. Dry cleaners must keep records of how much solvent they use and where it goes. Many states require dry cleaners to have secondary containment (a tray or basin under the cleaning machine) to catch spills, and some states mandate regular inspections. Improper disposal can contaminate groundwater and soil, which is why regulations have become stricter over the past two decades.

Why dry cleaners choose one solvent over another

The choice of solvent depends on cost, speed, fabric compatibility, and local regulations. Perc is the cheapest and fastest option, which is why it remains dominant despite health concerns. Hydrocarbon solvents cost more but are less toxic. Liquid CO₂ is the gentlest on fabrics but requires expensive equipment and takes longer, so it is usually reserved for delicate or high-value items.

Local regulations also push the choice. Some states have banned perc or set important date for phasing it out, forcing dry cleaners to switch. California, New York, and several other states have restrictions on perc use or storage. A dry cleaner's choice of solvent is often a balance between what works best for their customer base, what they can afford, and what their state allows.

Frequently Asked Questions

Is perc still safe to wear on clothes after dry cleaning?

Perc evaporates during the drying process, so the amount remaining on finished clothes is very small. However, some perc may linger in the fabric, especially if clothes are not fully dried. Hanging dry-cleaned clothes in a well-ventilated area for a few hours before wearing or storing them can help any remaining solvent evaporate.

Can I ask my dry cleaner what solvent they use?

Yes. Most dry cleaners will tell you whether they use perc, hydrocarbon, or another solvent. If they do not know or will not say, that is a sign they may not be transparent about their practices. Some dry cleaners advertise their solvent choice as a selling point, especially if they use a safer alternative.

What is the smell from dry cleaning?

The smell is usually perc or hydrocarbon solvent. Perc has a sharp, chemical odor that some people find strong. Hydrocarbon solvents smell more like gasoline or mineral oil. Liquid CO₂ cleaning produces little to no odor. If the smell is very strong or lingers on clothes for days, it may mean the clothes were not fully dried.

Are there dry cleaners that do not use any chemicals?

All dry cleaning requires some solvent to dissolve oils and grease — water alone does not work. However, some dry cleaners use gentler solvents like liquid CO₂ or hydrocarbon, and some offer wet cleaning (a water-based process with special detergents) for certain garments. Ask your dry cleaner about their options if you want to avoid perc.

What happens to the used solvent after cleaning?

Used solvent is filtered to remove lint and debris, then either recycled (distilled and reused) or sent to a licensed waste disposal facility. It is not poured down the drain. Regulations require dry cleaners to track and document how much solvent they use and where it goes to prevent environmental contamination.