Dry Cleaning

Cleaning in Solvent Instead of Water

Dry cleaning exists for the garments water would harm. Some fabrics shrink, distort, bleed dye or lose their finish in water, and some garments are built with linings, padding and trims that behave differently from the outer cloth when wet, so a cleaning liquid that is not water is needed. Dry cleaning is any cleaning process for clothing and textiles using a solvent other than water, and the solvent dissolves the greasy soils that bind dirt to fabric while leaving water-sensitive fibers, dyes and constructions unharmed. The term is a misnomer, as most dry cleaning is done with liquid chlorinated hydrocarbon solvents, one of the most popular of which is perchloroethylene, commonly referred to as Perc: the clothes come out of a bath of liquid, and the dry in the name refers only to the absence of water, not to the absence of wetting.

The machinery reflects the economics and hazards of working in solvent. A dry cleaning machine is somewhat similar to a domestic washing machine, with the exception that it is significantly larger, and that all the dry-cleaning solvent is captured, filtered and re-used during the cleaning cycle rather than flowing down the drain. Washing, extraction and drying happen in the same closed machine, so solvent is recovered from the garments instead of evaporating into the shop or escaping with wastewater. That closed loop is essential twice over: solvent is expensive to replace on every load, and the solvents used are substances that must not be released casually. The filter's job matters to the customer as well, because solvent reused load after load must be kept clean or it will redeposit soil on the next batch of garments instead of removing it.

Gasoline, Perc and the Search for Alternatives

The industry's solvent history is a progression away from danger. Early dry cleaners used solvents such as gasoline and kerosene, effective grease cutters that made the early cleaning shop a serious fire risk. After World War II, carbon tetrachloride and trichloroethylene were popular before giving way to Perc, as the trade moved to non-flammable chlorinated solvents that could be used at larger scale with less fire danger. Perc solved the fire problem and cleaned excellently, which is why it became the standard, but it brought a different cost: Perc is toxic, and long-term exposure can cause liver and kidney damage. Handling rules, machine design and ventilation in modern plants are all shaped by the need to keep workers' exposure low and to keep the solvent contained through the whole cycle.

Fortunately, there are healthier alternatives, and a modern cleaner may offer several processes and choose between them by garment. Wet cleaning with biodegradable soap and water, carefully controlled in machines that regulate temperature and agitation, can clean many garments once considered dry-clean only. Silicon-based solvents and liquid CO2 solvents clean in genuinely different chemistries, gentler on some fabrics and decorations, and alternative hydrocarbon solvents occupy a middle ground of familiar process with a different risk profile. For the customer, the practical points survive every chemistry: dry cleaning is the route for structured, lined, water-sensitive and formally finished garments; the care label's instruction should be followed because it reflects the garment's weakest component; and a cleaner's willingness to discuss which solvent a garment will meet is a fair sign of a careful shop.