TUCSON, Ariz. — William “Bake” Shaffer knew the dry cleaning industry was on the brink of something big 10 years ago.

It was at that time when Exxon Mobil Corp. released a new chemical substance that could be used as a cleaning solvent in the giant washing chambers at dry cleaning facilities.

Tucson’s own Shaffer Dry Cleaning & Laundry is one of a growing number of dry cleaning businesses that uses a nontoxic hydrocarbon cleaning solvent. This substance replaces the traditional tetrachloroethylene solvent — otherwise known as PCE or "perc" in dry-cleaning lingo — which, since the 1940s has been the chemical of choice for the dry cleaning industry.

The solvents that go into the chambers produce a tar-like byproduct that collects in trays at the back of the machines. This byproduct contains portions of the solvent along with the gunk and dirt embedded in clothing fibers.

“Hydrocarbons register at between zero and one on the environmental toxicity scale, whereas perc is about a nine or 10,” said Shaffer, who owns nine stores in the Tucson area. “We don’t have to worry about hazardous waste risks anymore, even though I have a hazardous waste guy show up every couple months to haul this stuff away."

PCE, although relatively harmless in small concentrations, is a ground soil contaminant. It can seep into the ground from spillage or leakage in the septic systems and dry wells of commercial cleaning facilities, Shaffer said.

PCE users often must contend with waste disposal protocols in accordance with the Resource Conservation Act because of the substance’s toxicity and the risk it poses to human health. California, for example, passed a statute in January 2007 that initiates a 15-year phase-out of the substance and its use in dry cleaning facilities.

Shaffer pays $10 per gallon for the hydrocarbon-based cleaning solvent, which he recycles to cut down on costs.

“Cost isn’t a big factor because we can recycle all our dry cleaning solutions through distillation,” Shaffer said. “Hydrocarbon isn’t in terribly high demand right now because perc is still the most-used solvent in dry cleaning stores in cities."

In addition to its gentle touch on the environment, the hydrocarbon solvent has a couple of aesthetic benefits, including its noticeably mild scent compared to the sweet chlorine-like smell of PCE. The hydrocarbon cleaner also leaves a shiny luster on many fabrics, Schaffer said.

“The one drawback to using it is that it sometimes isn’t as consistent a cleaner as perc, especially when you’re dealing with oil or grease stains,” Shaffer said. “We do a little more spot treatment on clothes with those kinds of stains.”

Shaffer, who employs 78 and has a customer base of about 18,000, expects the industry to continue to make its slow transition from perc to hydrocarbon in the coming years.

"It's a great way to keep the regulators off our backs and do the environment some good at the same time," Shaffer said.

Despite its increasing popularity, hydrocarbon solvent is far from taking over PCE as the solvent-of-choice. At Laundry & Cleaners Supply, Inc., in Phoenix, more than half of the orders for cleaning solvents are for PCE.

"It seems like there's a lot of imbalance in the industry, but the truth is that I do business with dry cleaning owners who use both solvents," said Dave, a manager at Laundry & Cleaners Supply, Inc., who asked not to be fully named. "I would say, though, that I definitely fill more perc orders."

Dave's supply distribution company sells PCE for $14 per gallon. It remains the prefered solvent among the majority of dry cleaners, he argues, because it is still the most efficient and reliable de-greasing cleaner.

"Pricing in the dry cleaning market is a negotiable thing," Dave said. "It's more an issue for a lot of dry cleaning business of how they can be most efficient given their resources."

Heath Bowlin, the owner of 15 Sparkle Dry Cleaning stores in the Tucson area, is unabashedly in favor of perc as the dry cleaning solvent-of-choice. He said advances in dry cleaning washing machine technology and safer disposal practices have significantly reduced environmental risks.

Bowlin said he also believes that Shaffer Dry Cleaning and Laundry, in particular, has overstated the proported benefits of hydrocarbons.

"Hydrocarbon solvents are actually a slight step above diesel products," Bowlin said. "If you think this is a good solution for the environment, I think you're crazy. Keep dreamin' man."

Bowlin arranged for air quality tests in his stores that revealed the concentration of perc to be zero parts-per-million.

"I'd say that I'm a green cleaner in terms of how I use the latest technical controls," he said.

The industry insider at Laundry & Cleaners Supply, Inc., also thinks that many of the environmental concerns associated with PCE are nominal because of how its disposal is regulated.

"At the end of the day, people take their clothes to dry cleaners to get them sharp-looking and pressed," he said. "Let's just clean the clothes and let the businesses decide how they want to do that."