Dry cleaning is any cleaning process for clothing and textiles using a solvent other than water.
Dry cleaning still involves liquid but is so named because the term 'wet' is specific to water; clothes are instead soaked in a water-free liquid solvent, known as perchloroethylene, which is the most widely used solvent. Alternative solvents are bromopropane and petroleum spirits.Most natural fibres can be washed in water but some synthetics (e.g. viscose, lyocell, modal, etc.) react poorly with water and must be dry-cleaned.
A dry-cleaning machine is similar to a combination of a domestic washing machine and clothes dryer.
The solvent temperature is maintained at 30 degrees Celsius (86 degrees Fahrenheit), as a higher temperature may damage it.
Garments are also checked for foreign objects. Items such as plastic pens may dissolve in the solvent bath, damaging the textiles. Some textile dyes are "loose" and will shed dye during solvent immersion.
Not all stains can be removed by dry cleaning. Some need to be treated with spotting solvents — sometimes by steam jet or by soaking in special stain-remover liquids — before garments are washed or dry cleaned. Also, garments stored in soiled condition for a long time are difficult to bring back to their original color and texture.
A typical wash cycle lasts for 8–15 minutes depending on the type of garments and degree of soiling.
At the end of the wash cycle, the machine starts a rinse cycle where the garment load is rinsed with distilled solvent. This solvent rinse prevents discoloration.
Modern machines recover approximately 99.99% of the solvent employed.
During the drying cycle, the garments are tumbled in a stream of warm air (60–63 °C). The air temperature is controlled to prevent heat damage to the garments.
Modern dry cleaning machines use a closed-loop system in which the chilled air is reheated and recirculated. This results in high solvent recovery rates and reduced air pollution.