Is water needed during the dry cleaning process?
Release Time:
2011-09-02 13:33
Source:
www.chinalaundry.cn
Li Wenhao
Some people might ask when they see this question: "If there is water during the dry cleaning process, doesn't it become wet cleaning? Can it still be called dry cleaning?"
But in fact, this is not the case. Dry cleaning is a laundry process completed by placing clothes into a dry cleaning machine filled with dry cleaning solvent, relying on the solvent's dissolving power, the mechanical force of the dry cleaning machine, and the interaction with special dry cleaning detergents. However, a certain amount of water is indeed required during the dry cleaning process. This is mainly because stains on clothes can generally be divided into two types: one is oily stains, which can be dissolved and removed by dry cleaning solvents during dry cleaning; the other is water-based stains, which only dissolve in water. If there is only dry cleaning solvent without water during the dry cleaning process, water-based stains cannot be effectively removed. Therefore, the presence of an appropriate amount of water during dry cleaning is absolutely necessary.
Everyone knows that dry cleaning solvents (dry cleaning oils) and water are completely different substances and are immiscible. The specific gravity of water is 1.0, while that of petroleum-based dry cleaning solvents is about 0.75 to 0.8. If water is directly added to dry cleaning oil, the water will settle below the oil. This oil-water separation not only fails to achieve the cleaning and stain removal effect but also causes adverse effects such as shrinkage, wrinkling, fading, and reverse contamination of clothes.
During the dry cleaning process, water comes from two sources: first, any clothing absorbs varying degrees of moisture in any environment, so worn clothes naturally bring some moisture when placed into the dry cleaning machine; second, before placing clothes into the dry cleaning machine, a pre-stain removal treatment is performed, usually by spraying a dry cleaning special aqueous stain remover containing a certain proportion of water onto the soiled local surfaces of the clothes, followed by the dry cleaning machine washing procedure.
How to keep the moisture in the dry cleaning machine preserved in the dry cleaning oil and make the moisture work better? Dry cleaning operators must use dry cleaning additives (soap, dry cleaning soap) to achieve this. Soap is a synthetic surfactant, with each soap molecule containing a lipophilic group and a hydrophilic group. When soap is added during dry cleaning, its molecules bring water molecules and dry cleaning oil molecules together, so the water molecules are evenly distributed in the dry cleaning oil, making free water invisible. Because there is no free water, phenomena such as shrinkage, wrinkling, fading, and reverse contamination of clothes do not occur; it is precisely because of the presence of an appropriate amount of water molecules in the dry cleaning solvent that water-soluble stains on clothes can be effectively removed during dry cleaning.
If dry cleaning operators do not have petroleum solvent distillation recovery equipment, they must pay even more attention to the quality management of petroleum solvents to maintain the purity of the petroleum solvent and thus improve the quality of dry cleaning.
(Author's affiliation: Deputy General Manager of Shanghai Weishi Laundry Equipment Co., Ltd.)
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