You go to your dry cleaning store, drop off your clothes, get your ticket, then drive away. Later, you return, pick up your clothes, pay the customer service representative, and drive away again.
But, do you know what happened to your clothes while they were at the dry cleaning shop? Do you know what dry cleaning is and how it works?
Dry cleaning dates back to ancient times, probably beginning with the advent of textile clothing itself. The ruins of Pompeii gives a record of a highly developed trade of *fullers* who were professional clothes cleaners. Lye and ammonia were used in early laundering, and a type of clay known as *fuller*s earth* was used to absorb soils and grease from clothing too delicate for laundering.
There are many stories about the origin of dry cleaning, all centering on a surprise discovery when a petroleum-type fluid was accidentally spilled on a greasy fabric. It quickly evaporated and the stains were miraculously removed. The firm of Jolly-Belin, opening in Paris in the 1840s, is credited as the first dry cleaning firm.
In spite of the name, dry cleaning is not completely dry. Fluids are used in the dry cleaning process. In the early days, garment scourers and dryers found several fluids that could be used as dry cleaning solvents, including camphene, benzene, kerosene, and gasoline. These fluids are all dangerously flammable, so dry cleaning was a hazardous business until safer solvents were developed.
There are various makes/models of dry cleaning machines, but they all work on the same principle. A dry cleaning machine consists of four basic components:
- Holding or base
- Tank
- Pump Filter
- Cylinder or wheel
The holding tank holds the dry cleaning solvent. A pump is used to circulate the solvent through the machine during the cleaning process. Filters are used to trap solid impurities. A cylinder or wheel is where the garments are placed to be cleaned. The cylinder has ribs to help lift and drop the garments.
The operation of the dry cleaning machine is easy to understand. The solvent is drawn from the tank by the pump. The pump sends the solvent through the filters to trap any impurities. The filtered solvent then enters the cylinder to flush soil from the clothes. The solvent leaves the cylinder button trap and goes back to the holding tank. This process is repeated throughout the entire cleaning cycle, ensuring that the solvent is maintained to give effective cleaning at all times.
After the cleaning cycle, the solvent is drained and an *extract* cycle is run to remove the excess solvent from the clothes. This solvent is drained back to the bare tank. During extraction, the rotation of the cylinder increases in order to use centrifugal force to remove the solvent from the clothes. Once the clothes have finished extracting, the cylinder stops. At this time, clothes are either transferred to a separate dryer or, on most machines, dried in the same unit, a closed system. The drying process uses warm air circulated through the cylinder to vaporize the solvent left on the clothes. The solvent is purified in a still. Here the solvent is heated. The vapors are then condensed back to a liquid leaving behind all impurities in the still. This clean solvent is then pumped back into the holding/base tank. At Waldens we have a system for reclaiming most of the solvent used to be used again in the next batch. This cuts down significantly on the amount of solvent needed and prevents the release of chemicals into the environment.
