Rumor: [the black curtain of dry cleaning] water washing pretends to be dry cleaning and toxic chemical products… Recently, after investigation, it was found that almost all the clothes of XXX and XXX laundries were water washed; And professional detergent is actually cheap detergent; The dry cleaning agent is tetrachloroethylene, a toxic chemical product, which fades after washing and hides after dyeing; The single piece charge is ten times the washing cost.
Truth: Recently, a number of media have exposed the “black curtain” of the laundry industry. The fraud involved and whether the price is reasonable are beyond the scope of scientific discussion. However, whether the accusation that “dry cleaning agents poison clothes” is reasonable is worth discussing.
what is dry cleaning
Dry cleaning is relative to water cleaning. Most of our daily cleaning is achieved by using water as a solvent, while dry cleaning uses organic solvents instead of water to clean fabrics.
If the stains on the fabric are classified according to their solubility, they can be roughly divided into two categories: fat solubility and water solubility. Most of these stains, especially those that are difficult to clean such as blood, milk stains and oil stains, belong to fat soluble substances. They are not easy to combine with water, and the cleaning ability of conventional water washing process is poor. It is easier to use organic solvents with strong fat solubility to clean such substances. This is the same reason that working people thought of using kerosene to clean oil stains on clothes in the early years.
Another advantage of using organic solvents is that they cause less fiber damage to some fabrics than water. In addition, organic solvents can also kill more microorganisms during cleaning.
is tetrachloroethylene a dry cleaner that should not be used
Because of these characteristics of dry cleaning, when choosing which organic solvent (or a combination of several chemical substances) as the dry cleaning agent, the key indicators are the solubility of fat soluble substances, the damage of dry cleaning agent to fiber and chromaticity, and its bactericidal ability. In addition, from a practical point of view, it also depends on whether the dry cleaning agent can be removed from the clothes as easily as possible after cleaning, as well as the cost, toxicity and other factors of the dry cleaning agent.
Compared with kerosene, gasoline and other petroleum hydrocarbon solvents, tetrachloroethylene is indeed more toxic, but it has obvious advantages in other aspects, so until now, it is still the dry cleaning agent used by most dry cleaners and also the permitted dry cleaning agent.
Although it is permitted to use, toxicity is the most important concern for consumers.
how to make tetrachloroethylene safe
In fact, consumers do not need to worry about safety. The dose of tetrachloroethylene exposed to dry cleaned clothes is extremely limited, which is far from enough to cause allergy, anesthesia and other symptoms, and will not cause liver toxicity, cancer and other toxicities that require larger dose and longer-term exposure. This can be seen from the steps of dry cleaning.
Similar to daily water washing, the dry cleaning of clothes can be roughly divided into three steps: immersing the clothes in the solvent, making the stains fully contact with the solvent by rolling and stirring, and being taken away from the fabric (in water washing, because most of the stains are insoluble in water, this process needs the assistance of detergent); Centrifuge to remove the dry cleaning agent (because there is no need to add detergent, there is no rinsing step in water washing); Heat to further remove the dry cleaning agent from the fabric (the volatile organic solvent is stronger than water, which is easy to remove from the fabric, but the drying process will still raise the temperature to about 80 ℃ and stay for 15 minutes to ensure that the dry cleaning agent is removed as much as possible).
If consumers are still not confident about the clothes that have undergone this harsh drying process, you can also hang the clothes just taken back from the dry cleaner for a day or two before putting them in the cabinet.
The amount of residual tetrachloroethylene on the dry cleaned fabric is very low even if it is tested by the most sophisticated instrument analysis method at present. If it is left for a few more days, the residual tetrachloroethylene on the fabric can hardly be detected even under the condition of no ventilation. Considering that the clothes sent for dry cleaning are usually not worn close to the body, the possibility of contact is even less. Consumers do not need to worry about their own safety.
What we really need to worry about is the environment of the dry cleaning shop and the operators there.
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