Dry cleaner solvent is a chemical that is used to remove fabric stains during the dry cleaning process. Dry cleaning is a method of cleaning clothing, bedding, and other fabrics, that does not require the items to be submerged in water and treated with liquid detergent. Certain fabrics, such as rayon, wool, and silk, are too delicate or are prone to losing their shape and texture when exposed to liquid. These fabrics often come with warning labels that advise the items be professionally dry cleaned only using a solvent and not washed in water by hand or in a washing machine.
The most widely used form of dry cleaner solvent tends to be perchlorethylene, also more commonly referred to by dry cleaners as "perc." It is a non-flammable chemical solvent that can dissolve the molecules that form stains, allowing them to be removed from the fabric. Prior to the development of perc in the 1930s, other dry cleaner solvents were effectively used; however, these solvents tended to be flammable and could be highly dangerous.
Dry cleaner solvent is typically kept in a holding tank of a dry cleaner machine. The item to be cleaned is placed into a moving cylinder to keep it in place and the solvent is pumped throughout the cylinder to remove any soil from the fabric. Once the solvent has penetrated the fabric to clean it, the dry cleaning machine runs an extract cycle, which is intended to remove any remaining solvent and place the item back into the holding tank. The cylinder holding the clothing revolves more quickly during the extract cycle to ensure no solvent is left behind on the fabric. The final step in the dry cleaning process is usually drying, in which the cleaned items are moved to a drying area of the machine where warm air is circulated in order to gently vaporize any solvent remaining in the fibers of the fabric.
Due to the chemical ingredients in dry cleaner solvent, it may have potentially negative consequences for the environment. If large amounts of the solvent are emitted into the air from a dry cleaning machine, the fumes may cause pollution in the air. Some government agencies, such as in the United Kingdom and the United States, have regulations in place on how to safely handle dry cleaner solvent. Dry cleaner shop owners may be required to have a permit authorizing them to handle the solvents and their dry cleaning machines may be inspected to ensure they are not releasing excessive amounts of solvent into the air.