A dry-cleaning machine is similar to a combination of a domestic washing machine and clothes dryer. Garments are placed in the washing or extraction chamber (referred to as the “basket” or “drum”), which constitutes the core of the machine. The washing chamber contains a horizontal, perforated drum that rotates within an outer shell. The shell holds the solvent while the rotating drum holds the garment load. The basket capacity is between about 10 and 40 kg (20 to 80 lb).
During the wash cycle, the chamber is filled approximately one-third full of solvent and begins to rotate, agitating the clothing. The solvent temperature is maintained at 30 degrees Celsius (86 degrees Fahrenheit), as a higher temperature may damage it. During the wash cycle, the solvent in the chamber (commonly known as the “cage” or “tackle box”) is passed through a filtration chamber and then fed back into the “cage”. This is known as the cycle and is continued for the wash duration. The solvent is then removed and sent to a distillation unit consisting of a boiler and condenser. The condensed solvent is fed into a separator unit where any remaining water is separated from the solvent and then fed into the “clean solvent” tank. The ideal flow rate is roughly 8 liters of solvent per kilogram of garments per minute, depending on the size of the machine.
Garments are also checked for foreign objects. Items such as plastic pens will dissolve in the solvent bath and may damage textiles beyond recovery. Some textile dyes are “loose” (red being the main culprit), and will shed dye during solvent immersion. These will not be included in a load along with lighter-colour textiles to avoid colour transfer. The solvent used must be distilled to remove impurities that may transfer to clothing. Garments are checked for dry cleaning compatibility, including fasteners. Many decorative fasteners either are not solvent proof or will not withstand the mechanical action of cleaning. These will be removed and restitched after the cleaning, or protected with a small padded protector. Fragile items, such as feather bedspreads or tasseled rugs or hangings, may be enclosed in a loose mesh bag.
Not all stains can be removed simply 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 colour and texture. Natural fibers such as wool, cotton, and silk of lighter colours when left in dirty or soiled condition for long times are unlikely to be restored to their original colour and finish.