Dry cleaning, despite what the average person may think, is actually a bit of a misnomer. There is nothing dry about it. The clothes get just as wet as when you wash them. However, unlike traditional clothes washing, the cleaning solvent is not water-based, which is how the process got its name.
The dry cleaning process involves the use of solvents to get the a garment cleaner. In most cases, a solvent called perchlorethylene (perc), is used by the vast majority of dry cleaners in the United States and other industrialized nations. It replaced other harmful chemicals that were not as effective and more dangerous to use.
Much like one may go through laundry at home and look for stains and pretreat them, the same thing is done before dry cleaning takes place. The pretreatment helps loosen up any soils in the fabric so that the solvent can be a more effective cleaner. Once that is completed, the clothes are put in a machine and the solvent is added. After that, the garment may again be inspected for any major imperfections.
During the dry cleaning process, the portion that actually takes place in the machine is very similar to the type of process a garment may undergo in a home washing machine. A large steel basin, which is perforated, allows the solvent in and then creates a centrifugal effect in order to remove the solvent along with any dirt it catches. The solvent, usually perc, is then passed through a filter and is capable of being reused. Thus, the process becomes very economical for both the cleaner and, as a natural result, the customer.
Dry cleaning is necessary for fabrics that are delicate and may not do well in daily washing. This may be because the fabrics simply do not react well to water and soap. In some cases, it may be possible to either dry clean, or wash fabrics by hand. Most care tags will offer this option, if it is recommended. However, in most cases, hand cleaning will not be nearly as effective as dry cleaning, but it will substantially more economical.
In the past, a petroleum-based solvent was used in dry cleaning. However, these solvents posed considerable risks as they were highly flammable. Further, the solvent, itself, would often leave an odor on the clothing. While there may be cases, even in modern times, when products come back from the cleaners with an offensive odor, this is a rarity at most dry cleaners.