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History 
Pompeii - Fullonica of Veranius Hypsaeus. Employees of a fullonica and a customer (l), with garments hanging overhead The ancient Romans used ammonia (derived from urine) and fuller’s earth to launder their ever-present woolen togas. Fullonicae were very prominent industrial facilities, with at least one in every town of any notability, and frequently the largest employer in a district. These laundries obtained urine from farm animals, or from special pots situated at public latrines. The industry was so profitable that fuller’s guilds were an important political constituency, and the government taxed the collection of urine. Modern dry cleaning uses non-water-based solvents to remove soil and stains from clothes. The potential for using petroleum-based solvents in this manner was discovered in the mid-19th century by French dye-works owner Jean Baptiste Jolly, who noticed that his tablecloth became cleaner after his maid spilled kerosene on it. He subsequently developed a service cleaning people’s clothes in this manner, which became known as "nettoyage àsec," or "dry cleaning". Early dry cleaners used petroleum-based solvents, such as gasoline (petrol) and kerosene. Flammability concerns led William Joseph Stoddard, a dry cleaner from Atlanta, to develop Stoddard solvent as a slightly less flammable alternative to gasoline-based solvents. The use of highly flammable petroleum solvents caused many fires and explosions, resulting in government regulation of dry cleaners. After World War I, dry cleaners began using chlorinated solvents. These solvents were much less flammable than petroleum solvents and had improved cleaning power. By the mid-1930s, the dry cleaning industry had adopted tetrachloroethylene (perchloroethylene), colloquially called "perc," as the ideal solvent. It has excellent cleaning power and is stable, nonflammable, and gentle to most garments. However, perc was also the first chemical to be classified as a carcinogen by the Consumer Product Safety Commission (a classification later withdrawn). In 1993, the California Air Resources Board adopted regulations to reduce perc emissions from dry cleaning operations. The dry cleaning industry is now beginning to replace perc with other chemicals and/or methods. Traditionally, the actual cleaning process was carried-out at centralized "factories"; high street cleaners shops received garments from customers, sent them to the factory, and then had them returned to the shop, where the customer could collect them. This was due mainly to the risk of fire or dangerous fumes created by the cleaning process. At this time, dry-cleaning was carried out in two different machines  one for the cleaning process itself and the second to dry the garments. This changed when the British dry-cleaning equipment company Spencer introduced the first in-shop machines (which, like modern dry cleaning machines, both clean and dry in one machine). Though the Spencer machines were large, they were suitably sized and vented to be fitted into shops. In general, three models, the Spencer Minor, Spencer Junior and Spencer Major, were used (larger models, the Spencer Senior and Spencer Mammoth, were intended for factory use). The cleaning and drying process was controlled by a punch-card, which fed through the "Spencermatic" reader on the machine. Also, Spencer introduced much smaller 6 kg capacity machines, including the Spencer Solitaire and one simply called the Spencer Dry Cleaning Machine, for use in coin-operated launderettes. These machines resembled coin-operated tumble dryers; to be as small as they were, they simply filtered used perc, rather than distilling it like the commercial Spencer machines. Solvent had to be changed far more frequently as, without distillation, it quickly became discoloured and could cause yellowing of pale items being cleaned. A coin-operated version of the Spencer Minor, which automatically carried out all the distillation and solvent-cleaning operations of the standard version, was available but rarely seen, presumably due to its greater cost and size than the other coin-operated machines. During the 1970s and 1980s, Spencer machines were extremely popular, with virtually every branch of Bollom possessing either a Spencer Minor or a Spencer Junior. Spencer continued to produce machines (introducing new modular and computer-controlled models, such as the Spencer Sprint series) until the late 1980s, when the company closed. Spencer machines may still occasionally be seen. Machines of this era were called vented; their fumes and drying exhausts were expelled to the atmosphere, in the same way as with modern tumble dryer exhausts. This not only contributed to environmental contamination, but also much potentially reusable perc was lost to the atmosphere. Much stricter controls on solvent emissions have ensured that all dry cleaning machines in the western world are now fully enclosed, and no solvent fumes are vented to the atmosphere. In enclosed machines, solvent recovered during the drying process is returned condensed and distilled, so it can be reused to clean further loads, or safely disposed of. The majority of modern enclosed machines also incorporate a computer-controlled drying sensor, which will automatically sense when all possible traces of perc have been removed from the load during the drying process. This system ensures that only the smallest amount of perc fumes will be released when opening the door at the end of the cycle. Dry cleaning (or dry-cleaning) is any cleaning process for clothing and textiles using a chemical solvent rather than water. The solvent used is typically tetrachloroethylene (perchloroethylene), abbreviated "perc" in the industry and "dry-cleaning fluid" by the public. It is often used instead of hand washing delicate fabrics, which can be excessively laborious. 
Many dry cleaners place cleaned clothes inside thin clear plastic garment bags. Process 
Modern dry clean machine A dry-cleaning machine is similar to a combination of a domestic washing machine, and clothes dryer. Garments are placed into a washing/extraction chamber (referred to as the basket, or drum), which is 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’) 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 comprising 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 one gallon of solvent per pound of garments (roughly 8 litres 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-color textiles to avoid color 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 dry cleaning 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. The density of perchloroethylene is around 1.7 g/cm³ at room temperature (70% heavier than water), and the sheer weight of absorbed solvent may cause the textile to fail under normal force during the extraction cycle unless the mesh bag provides mechanical support. Many people believe that marks or stains can be removed by dry cleaning. Not every stain can be cleaned just 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. Natural fibers such as wool, cotton, and silk of lighter colors should not be left in dirty or soiled condition for long amounts of time as they absorb dirt in their texture and are unlikely to be restored to their original color and finish. A typical wash cycle lasts for 8–15 minutes depending on the type of garments and degree of soiling. During the first three minutes, solvent-soluble soils dissolve into the perchloroethylene and loose, insoluble soil comes off. It takes approximately ten to twelve minutes after the loose soil has come off to remove the ground-in insoluble soil from garments. Machines using hydrocarbon solvents require a wash cycle of at least 25 minutes because of the much slower rate of solvation of solvent-soluble soils. A dry-cleaning surfactant "soap" may also be added. At the end of the wash cycle, the machine starts a rinse cycle wherein the garment load is rinsed with fresh distilled solvent from the pure solvent tank. This pure solvent rinse prevents discoloration caused by soil particles being absorbed back onto the garment surface from the "dirty" working solvent. After the rinse cycle, the machine begins the extraction process, which recovers dry-cleaning solvent for reuse. Modern machines recover approximately 99.99% of the solvent employed. The extraction cycle begins by draining the solvent from the washing chamber and accelerating the basket to 350 to 450 rpm, causing much of the solvent to spin free of the fabric. Until this time the cleaning is done in normal temperature, the solvent is never heated in dry cleaning process. When no more solvent can be spun out, the machine starts the drying cycle. During the drying cycle, the garments are tumbled in a stream of warm air (60-63°C/140-145°F) that circulates through the basket, evaporating any traces of solvent left after the spin cycle. The air temperature is controlled to prevent heat damage to the garments. The exhausted warm air from the machine then passes through a chiller unit where solvent vapors are condensed and returned to the distilled solvent tank. 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. In the early days of dry cleaning, large amounts of perchlorethylene were vented to the atmosphere because it was regarded as cheap and believed to be harmless. After the drying cycle is complete, a deodorizing (aeration) cycle cools the garments and removes the last traces of solvent, by circulating cool outside air over the garments and then through a vapor recovery filter made from activated carbon and polymer resins. After the aeration cycle, the garments are clean and ready for pressing/finishing From Wikipedia, the free encyclopedia : Cleaning of clothing and textiles |
