Searching for the Perfect Cleaning Technology

Perchloroethylene, also known as perc, is the solvent used by about 75 percent of the nation's 35,000 dry cleaners, but not for much longer. With concerns about perc's health and environmental impacts mounting, states like California have begun to phase out the chemical and the hunt is on for cost-effective, less toxic cleaning technologies.

But replacing perc isn't simple. Companies now offer new cleaning systems that use a wide range of different cleaning methods, including hydrocarbons, CO2 or gycol. For Gordon Shaw, owner of Hanger Cleaners in San Diego, the technological flux in the industry means doing some heavy-duty research. Investing in new machines can be an expensive leap of faith in a system that may not stand the tests of time and commerce.

Last month, Shaw traveled to the Chicago offices of R. R. Street and Co. Inc., the venerable 131-year old dry-cleaning company. He was there to review a cleaning technology called Solvair that's even newer than the CO2 system he adopted for his business six years ago. He was impressed. "The people at Street tell me that Solvair is environmentally safe," says Shaw. And he says, "It does what we ultimately earn our living doing, which is clean clothes."

Because Solvair uses a proprietary technology and its long-term environmental impact is unclear, Shaw paid a visit to the company's headquarters to see how the system works. What is known about Solvair is that it uses a glycol ether solvent to wash clothes—glycol ethers are a family of chemicals used in everything from antifreeze to household cleaning products—and uses a CO2 process similar to what Shaw uses to dry them.

Still, Annette Kondo, a spokesperson for the Coalition for Clean Air, a California nonprofit that has worked on clean-air issues for more than 35 years, isn't sold on Solvair. "The future of dry cleaning, we believe, is not in solvents like Solvair but in nontoxic, nonchemical technologies like CO2 and wet cleaning, which has come a long way," she says.

Ross Beard, president and CEO of R. R. Street, disagrees: "Solvair works more effectively than perc, and it is environmentally friendly and occupationally safe." Beard notes that his company has been looking at dry-cleaning alternatives to perc for a decade and this one is "very promising." He adds that there are a "wide range of glycol ether products, and yes, some of them have issues. But the one we are using has shown no adverse environmental or health effects that we are aware of. It has been used in Comet and Lysol and other household cleaners for years."

Katy Wolf, a chemist and director of the Institute for Research and Technical Assistance, who has studied dry-cleaning technologies for decades, says there is no way for Shaw or anyone else to know the level of toxicity of the Solvair technology because Street will not disclose which glycol ether is being used, and because only a small number of glycol ethers have been tested for chronic toxicity anyway.

But, she points out, glycol ethers are VOCs (volatile organic compounds), which means they are emitted into the air after they perform their function. "A VOC is certainly better than a carcinogen, but who knows, it could be both," says Wolf. "The dry-cleaning industry is so secretive, we may never know exactly what type of glycol ether this is [if R. R. Street doesn't divulge the information]."

For the moment, Shaw continues on his search for a dry-cleaning technology that is nontoxic like CO2, but less expensive and a little better at breaking down dirt, grease and oil. In the meantime, he is very happy with his current system.

In the CO2 cleaning process, clothes are placed in the machine's washing chamber, then the chamber is emptied of air, and the pressure in the chamber is raised to approximately 700 pounds per square inch (psi) by injecting CO2. Then, liquid CO2 is pumped into the washing chamber. The cleaning cycle lasts about five to 15 minutes, and the whole process takes place at ambient temperature. The liquid CO2 goes into the fibers and dissolves dirt, fats and oils. During the washing cycle a filter cleans particles from the liquid.

At the end of the cleaning process, the liquid CO2 is pumped back into the storage tank, lowering the pressure in the cleaning chamber. On its way to the storage vessel, the gas is chilled and once again condensed into its liquid form. When the pressure is low enough, the remaining CO2 is vented. This process does not produce any new CO2.

Shaw has been fascinated with this system since he first saw a CO2 machine at a dry-cleaning industry convention in Las Vegas in 1995. "It intrigued me from the start, but I thought there was no way they could make that work," he says, adding that from 1995 to 1998, at every trade show he attended, he looked to see how the technology was developing.

Not surprisingly, the biggest questions Shaw had early on were tech-oriented. "I was using a technology and operating a machine that no one else anywhere near me had any experience with," he says. "There was excitement and anxiety, in equal parts. I knew I was going out on a limb with this."

With a perc machine, Shaw notes, there are pipes and pumps you can see, and it's operating at regular pressures. "You can open a lid and look in there," he notes. "But when you're working with 700psi, you lose ability to see anything and you often have to theorize what's gong on behind that thick stainless steel.

Unlike Shaw, the majority of dry cleaners who are moving away from perc aren't opting for the CO2 system because it is too expensive. Most instead are moving toward a hydrocarbon technology which has its own issues with air pollution. Hydrocarbon dry cleaning uses solvents in the same way perc machines do, but these petroleum-based solvents are considered less toxic than perc. Hydrocarbon solvents are descendants of the petroleum-based solvents used in the early days of dry cleaning. Supporters say they are cleaner, more environmentally friendly and less flammable than their ancestors, but hydrocarbon's critics say these solvents, such as ExxonMobil Chemical's DF-2000 and Chevron Phillips Chemical's EcoSolv are still VOCs, and the EPA has noted concern over their flammability.

The only two evidently benign dry-cleaning technologies are CO2, whose costs are prohibitive for all but the most high-end cleaners like Shaw, and wet cleaning, which has made technological advances of its own in recent years.

Chemist Katy Wolf believes that in the short term, most perc cleaners that are making the switch to another system will move to hydrocarbon technology because it works and it is less expensive than CO2. "But hydrocarbon is a VOC as well," she says. "I believe the next generation of dry cleaners will move to benign materials such as CO2, as its costs decrease over time, and water-based cleaning. I don't see Solvair as being a big part of the future."

But Shaw is keeping an open mind about Solvair and all the other new technologies on the dry-cleaning block. "I definitely want to stay green, but I also want to stay in business," he says. "I listen to what everyone has to say about these new technologies, then I make my own decision. That's that's how I've always run my business. So far, it's worked out pretty well."