Understanding the Dry Cleaning Process

Laundry has been a routine household task for generations. Whether the method involved beating clothes on rocks by a river or pressing buttons on high-tech washing machines, this task revolves around water and mechanical action, typically aided by soap or an alkali. An alkali's role is to saponify oils and remove common dirt and debris. In most cases, the soap suspends the soil as it loosens during the wash cycle, only for it to be flushed away during the rinse and spin phases.

When drying laundry at home, the options are either hanging clothes on a line to air-dry or using a gas- or electric-powered dryer to tumble them dry.

Dry cleaning, in contrast, is a distinct method. It involves cleaning clothes without using water. The cleaning agent is a liquid, and all garments are soaked and cleaned using a liquid solvent — the absence of water is why it’s called ‘dry.’ In this article, we’ll take a closer look at the dry-cleaning process so you can better understand what happens to your clothes once you leave them at the cleaners.

Dry Cleaning Evolution

The pursuit of cleaning clothes without soap and water dates back a long way. One of the early innovators was Thomas Jennings, a freed African American tailor in New York City. Unsatisfied with contemporary laundry methods, he patented a technique called dry scouring in 1821, claiming it could remove dirt and grease while maintaining the garment's original shape. Unfortunately, the details of his process were lost due to a 1836 fire that destroyed numerous patent documents. Jennings reportedly used the proceeds from his invention to support the abolitionist movement and helped organize the Legal Rights Association, which fought legal battles against discrimination [sources: Matchar, NIHF].

In 1855, Jean Baptiste Jolly, a French owner of a dye-works business, noticed that his tablecloth became cleaner after a kerosene lamp accidentally spilled on it. Through his dye-works company, Jolly introduced a new service called ‘dry cleaning.’

Early dry cleaners used various solvents, including kerosene, to clean fabrics and clothes. In the U.S., the dry-cleaning industry is relatively young, emerging only in the last 75 years. After World War II, the volatile synthetic solvents carbon tetrachloride and trichlorethylene were replaced by perchlorethylene (perc), which became the preferred solvent for the industry. It was safer to handle, cleaned more efficiently, required less bulky equipment, and could be used in retail locations offering quick, one-hour service.

Perc continues to be widely used in the dry cleaning industry, but there has been growing concern over its potential health risks. Short-term exposure through inhalation can cause irritation to the upper-respiratory tract and eyes, kidney issues, and neurological effects, among other health problems. Additionally, exposure to perc has been linked to various cancers in workers [source: EPA, Erickson]. The EPA mandated that dry cleaning facilities in residential buildings cease using this chemical by December 2020 [source: Burke]. California's ban on perc is set to take effect in 2023, and several other states are also considering bans [source: EPA].

In New York state, dry cleaning business owners must undergo special safety training, machines that use perc must be certified, and the businesses must keep records of their use of perc and other hazardous chemicals [source: NYC Business]. In California, concerns about perc's impact on air quality prompted the state to phase out its use by 2023 [source: California Air Resources Board]. A March 2021 article in the journal Frontiers in Public Health featured input from public health and environmental experts who urged the industry to switch to alternative solvents, though they cautioned that more research is needed to evaluate the long-term health effects of these alternatives [source: Ceballos].

The Process

When you leave your clothes at the dry cleaners, the staff follows a standard procedure that is consistent across nearly all dry-cleaning businesses today. Your garments go through these steps:

The following sections delve deeper into each of these steps.

Tagging

When you drop off your clothes, each order is carefully recorded. While the exact identification method may differ between cleaners, it typically involves counting the items and noting their descriptions (e.g., shirt, blouse, pants). The date of drop-off and the expected pick-up date are also recorded. A small colored tag is attached to each piece of clothing using a safety pin or staple, and it stays with the garment throughout the entire dry-cleaning process. An invoice is created, and customer details — including name, address, and phone number — are entered into a computer system to track the order.

For garments requiring special treatment, such as removing a red wine stain from a shirt or pressing a double crease in pants, a different colored tag is applied. After the clothing is cleaned, it undergoes a quality check, and the order is reassembled. This means that all the items are bundled together, ready for the customer to collect. Remember, each order is identified by a colored tag with a number to help the staff ensure that the right shirts and pants are paired and returned to the correct owner.

Should You Pre-treat Stains?

While advice varies, some dry cleaning websites suggest that pre-treating stains isn’t necessary, and some even caution against it, as it may make the stains harder to remove. Dry cleaners have specialized fluids for treating stains that work differently from the water you might use at home. However, it's crucial to inform your cleaner about any spills on your clothing, as the residue from these substances can cause issues during cleaning and potentially worsen the damage to the fabric [source: Captain Dry Clean].

If you're unsure of how to handle a stain, reach out to your cleaner and ask for advice on the best treatment to use.

Dry Cleaning

Although it's called dry cleaning, your clothes actually get wet during the process! While different brands and models of cleaning machines exist, they all operate based on the same fundamental principles. A dry-cleaning machine is a motorized washer/extractor/dryer that can hold between 20 to 100 pounds (9 to 45 kg) of fabric inside a rotating, perforated stainless-steel basket. This basket is part of a system that includes motors, pumps, filters, recovery coils, storage tanks, fans, and a control panel. In modern machines, the washing and drying functions are combined into a single unit. This design enables nearly all of the cleaning solvent, such as perc, to be recovered during the cleaning process, which is both environmentally friendly and cost-effective for the cleaner.

As the clothes rotate in the perforated basket, a continuous stream of clean solvent flows from the pump and filtration system. The solvent is sprayed into the basket and the chamber, soaking the clothes while gently agitating and pounding them against baffles inside the cylinder. The used solvent is constantly filtered and recirculated, ensuring that it is free of dirt and debris trapped in the filter.

For instance, a typical machine might pump solvent through the clothes at a rate of around 1,500 gallons (5,678 liters) per hour. The most commonly used solvent in the industry is perchloroethylene, or 'perc,' which is approximately 69 percent denser than water. In an 8-minute cycle, the clothes would be drenched with around 200 gallons (757 liters) of solvent during the mechanical action, providing more than enough liquid to effectively clean the garments.

The next phase of the process drains and rapidly spins the clothes to remove the solvent, followed by a drying cycle where warm air circulates through the garments. The remaining fumes and solvent are vaporized by the heat, condensed in cooling coils, and filtered through an additional air control to ensure the solvent is eliminated.

The distilled solvent is separated from any residual water (which may have remained in the clothing or system) and is returned to the tank as purified solvent. Because any water that may have condensed during the process floats on top of the perc, separating the two is relatively simple.

No matter which solvent the dry cleaner uses, the overall quality of cleaning, the extent of soil removal, the brightness of the colors, the freshness, the absence of odor, and the softness of the fabric all rely on the cleaner's ability to manage the filter, solvent condition, and moisture levels. Without consistent attention to these factors, the quality of cleaning can fluctuate from day to day.

Post-spotting

Post-cleaning stain removal, known as post-spotting, is another crucial part of quality control. This technique involves the use of professional equipment and specialized chemical solutions, including steam, water, air, and vacuum. The process is straightforward: stains that originated with water (such as from bean soup) require water or wet-side chemicals to remove, while stains from dry substances (like grease, oil-based paint, tar, or nail polish) require solvents or dry-side chemicals for removal.

In home laundry, most wet-type stains are typically removed during the wash cycle, but grease is not. Dry cleaning works the opposite way – it leaves the wet-side stains undisturbed while removing grease and oils during the cleaning cycle. The only exception is when a specially formulated dry-cleaning soap, known as an anhydrous emulsifier, is used during the cleaning process.

After the cleaning process is finished, the dry cleaner will inspect your clothes to check for any remaining stains. If stains persist, post-spotting is employed to remove them. While a skilled cleaner can eliminate most stains and dirt, there will always be a small number of very tough stains that may not be fully removed due to various reasons, such as:

Finishing

The concluding step of the dry cleaning process involves finishing, which includes pressing, steaming, ironing, and any necessary repairs to restore the garment. This stage is the least mysterious, as most dry-cleaning establishments have their professional finishing equipment openly displayed for customers to see.

After the clothes are cleaned, they undergo pressing or 'finishing.' The process includes the following steps:

The pressing machine's head applies pressure, while steam is dispersed from the bottom. Many machines not only release steam but can also vacuum it out simultaneously!

Industry Trends

In recent years, the demand for eco-friendly products has surged, driven by stricter government regulations and increased consumer awareness of environmental issues.

Alternative solvents have been developed as replacements for perc, including those made from silicone, corn-based chemicals, and hydrocarbon-based solvents [sources: NY.gov, Coons, Leverette].

The EPA, along with organizations like the Toxics Use Reduction Institute at the University of Massachusetts Lowell, has encouraged the dry cleaning industry to adopt professional wet cleaning, which uses water and biodegradable detergents in computer-controlled machines. Garments are then finished with tensioning and pressing equipment [sources: Onasch, Turi.org, EPA]. Some cleaners who switched to wet cleaning have reported savings in both energy and water use [source: Turi.org]. In Washington state's King County, which includes Seattle, grants have been offered to cover part of the $40,000 to $60,000 cost of transitioning to wet cleaning [source: O'Neill].

While some industry professionals remain skeptical about the effectiveness of wet cleaning compared to traditional dry cleaning, advocates argue that advances in wet cleaning technology now allow it to handle most fabrics effectively [source: Hay].