Dry cleaning

Dry cleaning is a widely used process in professional textile care that uses a chemical solvent instead of water to clean textiles. Even though for most clothes it is possible to use both a dry or a wet cleaning process to remove soils, it is possible that specific garments demand the use of dry cleaning, as water or detergents may harm their form, color and quality. Dry cleaning is, despite its name, not a dry process.  Garments are immersed in a liquid solvent instead of water. Usually, it 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.


History of dry cleaning

Dry cleaning dates back to the 19th century, with the use of petroleum-based solvents. The main problem with dry cleaning back then was flammability, so after after World War I, dry cleaners began using chlorinated solvents and in the 1930s the use of perchloroethylene (PCE or Perc). Perc proved to be excellent for cleaning most clothes, easily recycled and practically nonflammable.


Solvents used

Nowadays, there are many solvents used in dry cleaning. Perchloroethylene is still the one most widely used. However, environmental and safety regulations implemented in many countries force dry cleaners to switch to dry cleaning alternatives or wet cleaning.

1. Perchloroethylene: Perc, as the industry usually calls Perchloroethylene (PCE) has been widely used since the 1930s. It is very effective, recyclable, nonflammable and has low toxicity. However, scientific research has proved that Perc is a toxic substance, damaging to humans and the environment. Strict regulations force dry cleaners to slowly replace the use of Perc in Europe and the US.

2. Hydrocarbons: Those are petroleum-based solvents still popular in many laundries. They are considered combustible and dangerous pollutants of the environment. They are usually used for specific kinds of garments and soils.

3. Decamethylcyclopentasiloxane or “liquid silicone”: This solvent has gained ground the last few years by GreenEarth Cleaning, as a more environmentally friendly alternative to Perc.


How a dry cleaning machine works

In the market, there is a wide variety of machines. However, all dry cleaning machines consist of:
a. A base tank
b. A pump
c. Filters
d. Cylinder

Garments are immersed into the solvent in the cylinder. The solvent, stored in a base tank moves around thanks to a pump and filters trap solid particles that are leftovers of the process. After the garments are cleaned, the solvent returns to the tank to be used again. As with wet cleaning, clothes are drained in the rotating cylinder by the use of centrifugal force. Usually, clothes are dried in the same machine by a stream of warm air.