What is dry cleaning?

Dry cleaning means not using water but using some solutions to clean the cloth. Water can damage some fabrics, such as wool, leather and silk; Sometimes washing with a normal washing machine will damage the buttons, lace, kimsa and other delicate decorative accessories. So these items need to be dry-cleaned.

Dry cleaning chemicals

There are many types of dry cleaning solvents for each type of fabric. In the past, people used gasoline, kerosene, benzene, pine oil, which were flammable and dangerous solutions. In the 30s of the last century, some synthetic, non-flammable solvents, such as perchlorethylene (PCE) and decamethylcyclopentasiloxane (liquid silicon) were found and used to this day.

Bleaches are also often added with these solvents to remove soil dirt. The detergent may be added to the solvent before washing or during washing depending on the case, and it works: Provides moisture to help clean soil soaked in water; Prevent soil from sticking back to fabric; Make the conductor so that the solvent can make the cloth cleaner.

Dry cleaning process

Dry cleaning means not using water but using some solutions to clean the cloth.

Dry cleaning machine consists of 4 parts: A solvent chamber; A pump to put the solvent into the machine; Filter bags retain dirt; A cylinder or a rotating cage to hold the cloth to be washed.

During washing, the pump draws the solvent from the container through the filter bags to filter the residue if present, and then into the rotating cage. Here the solvent comes into contact with the fabric and removes dirt. Then the solvent returns to the original container and repeats the procedure.

After the fabric has been washed, the machine will operate the spin mode to remove the remaining solvent from the fabric. The washing bucket will spin at high speed to knock off the solvent drops from the fabric, just like a normal household washing machine.

After squeezing, the cylinder (washing bucket) stops, the fabric can be dried right in that cage if it is a closed system or transferred to a separate dryer. The solvent is retained, filtered again and put into the original container.

The history of dry cleaning technology

Dry cleaning has appeared since ancient times. Records of methods for cleaning vulnerable items were found in the ruins of Pompeii, the volcanic city Vesuvius buried in 79 AD. Back then, a lot of clothing was made of wool and shrunk if immersed in water. Washers used solvents such as ammonia (alkaline) and lye, and a special clay to remove stains, soil, sweat, and grease that adhered to the fabric.

The so-called first dry-cleaning in modern times may be the story of a clumsy maid who drops some kerosene on a greasy tablecloth. Kerosene quickly evaporated and she saw that the fabric that had been dropped with kerosene was cleaner than the others. After that accident , people have experimented a lot to determine which kind of solvent is best to remove grease. These include pine oil, kerosene, liquid derived from petroleum, gasoline and camphor oil.

The first dry cleaning service was provided in 1825 by the Jolly-Belin company in Paris. Of course, in Paris, because fashion is an important part of people's lives. The clothes were soaked in oil-filled tanks and then put into the washing machine , then dried to evaporate the pine oil.

The first dry cleaning service in the US also appeared at the same time. Thomas Jennings, an American tailor and inventor, used a "dry cleaning" method to clean clothes that could not be washed in the usual way. His method was patented in 1821 and Jennings had a successful business in apparel and laundry services in New York.

The biggest drawback of oil-based solvents is very flammable, so people tried to find alternatives. And in 1821, for the first time, a British physicist and chemist named Michael Faraday synthesized PCE. However, it was not until the early 30s that this solvent was used for dry cleaning, after a dry cleaner in the US named William Joseph Stoddard found a way to improve PCE into dry cleaning solvent. This substance was used a lot in the late 30s and early 40s due to oil scarcity during World War II.

Environmental and health concerns

PCE is a dangerous substance for both the environment and health, especially workers working in the laundry factory.

Although PCE is the most popular option for dry cleaning, it is very dangerous for both the environment and health, especially the workers at the laundry factory. Also, people who often wear dry cleaning clothes may be affected. If inhaling PCE vapors for a long time, they may experience dizziness, dizziness, blurred vision, loss of coordination and mild memory loss, skin rashes.

People who work in dry cleaning also have a risk of some cancers. If prolonged contact with these chemicals, they may suffer from esophageal, bladder, cervical, blood and non-Hodgkin's lymphoma. In addition, they are also at risk for other diseases of the nervous system, liver, kidney, and lungs.

There have been many studies on the relationship between PEC and cancer, especially PEC used in dry cleaning. After carefully reviewing previous studies and conducting experiments on PEC effects in mice, researchers concluded in 2014 that PEC exposure has a close relationship with some diseases. cancer. Similar to the EPA classification in 2012, scientists' research in 2014 also found that PEC is a human carcinogen, no matter which form it is exposed to. are dry cleaning workers at particularly high risk of bladder cancer.

Although not yet conclusive, the US Environmental Protection Agency (EPA) has also provided some evidence that PEC affects both male and female reproductive systems, altering fine structure. coincidence and reduced ability to conceive. There have also been some studies of congenital anomalies caused by PEC, but there are still few and there is not enough evidence to conclude.

PEC can evaporate into the air, dissolve in water and soil in places where it is produced or used and nearby areas. Most PEC in the atmosphere is emitted by the dry cleaning industry, according to the Agency for Hazardous Disease Registry and Monitoring (US). This compound decays very slowly in the atmosphere, so it can spread very far. PEC can be dissolved in water and absorbed into the soil through this solvent-contaminated wastewater. Most of this PEC quickly evaporates from water and soil, but the rest also decomposes very slowly and thus lasts a long time and can spread to a large area around the source of emissions.

The future of dry cleaning industry

According to IBISWorld, a market research company, currently there are about 36,000 dry-cleaners in the US alone. However, some sources of data show that these workers are decreasing, partly because of the new trend many people prefer to use clothes with normal materials, more durable fabrics, cheaper clothes. so many places in the US have fewer and fewer dry-cleaning shops.

Another reason is that there are many private dry cleaners, operating on a family scale, and when the older generation runs out of working age, the younger generation does not succeed, but moves to another profession. Environmental concerns are also changing this industry. For example, the state of California is phasing out the use of PEC in dry cleaning and replacing it with less toxic substances, such as water and carbon dioxide (CO ₂ ) washing.